I've got quite a few game ideas, but they're geared towards old-school hardware like the GB and GBC. So, where can I go to learn how to develop gameboy and gameboy color games?
You don't, nerd love that shit, just dev for the PC. Any gameboy dev kits would be a glorious relic of the past at this point.
you can program a game in a low level language (c++ for example) compile for a ds, put the image on a sd card and play it with a sd card chip thing. i did that once, fun times.
3dbuzz has a tutorial on how to do it, but i think u have to pay for it now. google maybe?
There is always flash.
Youll also get a more people playing your game if you make it in flash. Wont be very profitable since flash games are f2p (you might get sponsored though), but doubt youd be making a Gameboy game for money anyway.
I've got a friend who works on retro games, cleaning them and fixing them. He's got loads of reproduction carts in his shop that he's got no use for and offered to sell them to me for $20 per cart (I think he has over 500 carts.) I've also got the proper cable to connect the gameboy carts to a PC, so there's that. All I need is the knowledge on how to program the game to put on it.
I can't believe I didn't see that.
The best homebrew GBA tutorial out there is Tonc
http://www.coranac.com/tonc/text/toc.htm
all you have to do is by a flashable cart and USB cable to get ROMs off your PC, you can also run games in the VBA emulator