Where Can I Safely Save Money?
Many of us only learn the hard way. I'm one of those people. Get an idea of how things should be - after doing a little research - and then forge ahead. Undoubtedly, the first venture into building and flying a multirotor cost me a lot more than it should have. Not because I connected things wrong or didn't read the instructions, forums, YouTube posts, etc. and not because I didn't price shop at 100 different websites. I spent more than I should have because I didn't know where I could save money - I over built, which I think a lot of us do the first and/or second time around, and very simply because of what we've learned...
When you're in this hobby flying anything else, i.e. airplanes, pattern, sport, scale, etc. gliders or helicopters, you learn quickly that you really do get what you pay for. When you buy some off-brand parts that swear they're great but cost next to nothing, in the end, it only costs you more. Why? Because the part breaks easily or goes bad really quick, and then you fall out of the sky.
Remember that line said by Rockhoud in the movie Armageddon, "You know we're sitting on four million pounds of fuel, one nuclear weapon and a thing that has 270,000 moving parts built by the lowest bidder. Makes you feel good, doesn't it?", just as they were about to blast off? Sometimes, flying a helicopter with cheap knock-off 425mm blades and a motor that'll spin 18,000 RPM makes me feel that way. I know I feel a lot better using parts that weren't just spun off some machine in China where it was more important to make a million parts a week than to ensure they won't explode under pressure.
Now, building a multirotor isn't exactly the same as building something with only one rotor or prop. There are places where you can save money and still be wildly successful. But the big question is where? Probably this question is best answered with the places where you definitely do NOT want to save money and work backwards from there.
You will crash and there's no doubt it'll happen. Doesn't matter what you fly or how well you're trained, stuff just goes wrong. Maybe if you're an aerial photographer with some training under your belt, and you fly 1 time a week, probably it'll be a while before you have an emergency. For those of us who fly 250 racing quads, it's going to happen this week sometime, probably tomorrow! You can save money on your frame, but you need to make sure it will survive a crash. Paying a little more money for carbon fiber often helps. There are a lot of pure G10 or FR4 frames out there - only the really thick ones will survive a high speed crash. So yes, you can save money here, but be aware that rigidity and strength are still super important.
You know, Cobra motors are pretty darn cheap when you compare them to Tiger Motors. Cobra's have a bit thicker shafts, so honestly I think that actually while Cobras are cheaper, they survive crashes better. Beyond Cobra, going to DJI, Tarot, ARRIS motors, etc. none of these are going to give you too much trouble. The biggest concern here is whether the bearings can be replaced and what kind of bearings they come with. Bearings are NOT an item that you want to scrimp on. However, consider that if you're flying anything from a hexacopter and above, if a motor gives out or has trouble, that usually doesn't result in a crash. Quads don't become tricopters very well at all.
Electronic Speed Controllers
There are super cheap ESCs that work pretty darn well, and cheap ones that suck. Period. Paying a lot for your ESCs, you should be getting something like KISS ESCs or SN20a's or Rotorgeek's 12amp ESCs. None of those are really all that expensive, with the exception of KISS ESCs, but this depends on whether you want super performance or not, too. Buying some of these super cheap $4 ESC's from China, it's a crap shoot - and honestly, I wouldn't trust them. Stick with reliable units that are talked about in the forums. That said, I've had DJI ESCs go bad on me, in the air. Luckily, I was flying a hex - not a big deal. It does happen, though...
There are less expensive flight controllers like the Naze32 which is $25 bucks at most places. For larger multirotors, we have the Naza-M v2 and Naza Lite. These are excellent units - but if you really want to save money, you can consider the Tarot flight controller, which is $129 bucks and according to the guys in the forums, it works great. Eagle Tree System's Vector is a good one, but it's not less expensive than the Naza, although it does come with an excellent OSD built-in! Others, in my opinion, are a crap shoot. Buying something from RCTimer because it's a lot cheaper - well it might work, but do you want to put even a $500 GoPro 200 feet in the air and trust it with $160 flight controller? Of course, that said, DJI's controllers have flown away, out of control as well. I think the flight controller is probably not somewhere that you want to save money, especially if you have a large expensive rig. Flying racing quads, you can't beat a $25 controller. Do buy the "real" Naze32 and CC3D boards though - buying the clones is not a good idea. They break easier and malfunction.
Most receivers are fairly inexpensive, unless you're flying with a Futaba radio. Even then, there are good options as the FrSky TFRSB works great with the Futaba and it's a $40 receiver. I wouldn't try to go super cheap here with some unknown knock off from China, though. I mean, this is your only link with your aircraft!
You can buy less expensive $20 5.8Ghz 600mw transmitters. In order for them to work, you'll need to buy a very good noise filter, which might increase the price a bit. You can make your own noise filters, but although I've had "some" luck in building my own, I've gotten better results with higher quality filtering, and by the time I was done, I'd added quite a bit of weight. So spending $70 bucks on an Immersion 600mw 5.8Ghz or 700mw 2.4Ghz transmitter, I think that's a little high. They do just work - they have voltage regulators and filtering built in, which has a lot to be considered. But if you're on a tight budget and weight isn't super critical, you can save a few bucks here.
I've seen some really cheap cameras for sale that work just perfectly fine. I personally like to buy either the Fatshark's or the PZ0420's from securitycamera2000.com for $30 bucks. If you find something less expensive, just be sure you can configure the camera's settings and that it has a decently wide field of view. If the cheap camera will allow you to switch out it's lens, then you can probably increase your field of view with a 2.8mm or 2.1mm lens.
I save money on batteries all the time. Price shop and make sure you're buying the correct C rating. There are "some" brands to stay away from like Zippy. Those are a crap shoot and often perform well when you first get them and go downhill quickly afterward. However, I wouldn't hesitate to try saving a few bucks where you can here.
Otherwise, you'll need a lot of other things in order to build, like heat shrink for wires and tools, and the list goes on and on - see my previous articles. Save money on tools where you can, and anything extra like antennas and velcro and ancillary stuff. Stick with solid motors, solid electronics - sometimes try the cheap stuff and definitely save money on batteries where you can.
Buying the best won't always make you the fastest, but it'll definitely make your crashes more expensive!
Good Luck and Happy Flying!