.... one of my biggest needs is WHERE DO YOU BUY GEARS???? i've looked all over and only found a few spotty places that sell a few gears, can anyone offer a suggestion as to were i can find spur gears for a drive train?
It would help to fill in your location info. You could be anywhere in the world, and everything isn't available anywhere.
For a bicycle drive, what you would want to use is the 16- or 12-diametrical-pitch hardened steel gears, with a 20- or 25-degree pressure angle. Helical-cut gears would be the quietest, but they would cost 2X what straight-cut gears would.
In the USA, McMaster-Carr sells some 16- and 12-dp steel straight-cut 20-degree spur gears, but they are not hardened (if you had access to an oxy-acetylene torch you could try to flame-harden them yourself). Even at that, they are fairly expensive. The plain-bore ones are cheapest and most-versatile but you need to be able to machine the bores and cut keyways into them to use them.
Stock Drive Products (also USA) sells hardened steel gears, but they are miniature--the largest diametrical pitch they offer is 24, which is too small for a bicycle drive. And despite the small sizes, the prices are still pretty surprising.
If you desire to make your own mix-and-match reduction gearing, the easiest way is to use roller chain (yes bicycle chain) and make your own sprockets in any size you want, from flat sheet steel. It can be done passably well with just a drill press and an angle grinder.
You still need a way to mate & key your home-made sprockets to a shaft, but you can make a klunky shaft fitting with just a hacksaw and drill press too. The one problem you *might* have is that you need to be able to bore a hole that is the same diameter as the shafts you are using. Most common home-size floor drill presses top out at 1/2-inch, which might work but is a bit thin IMO unless you use hardened-steel shafting. (McMaster does sell 1/2" dia hardened steel keyed shafting, btw)
Also,,, all this above assumes that the largest single gear reduction you have is the last one, between the reduction case and the rear wheel.
Unfortunately, the cost of producing steel gears means that there is very few places that produce mix-and-match sizes.
If you like building small mechanical stuff, Stock Drive Products has a LOT of cool parts--but they're all way too small for even a bicycle drive.