Unfortunately you'll be extremely lucky to find any of that for $30. You might get a non backlit mini for $30 if you keep an eye on ebay though. The only time I've ever seen a backlit system for sale it was $150 and honestly that's not a bad price when you consider the work that goes into modding in the light, coupled with the fact that the console has held up it's value quite well and commonly sells for about $60 these days. As for the flash cart, I know a lot of people here (myself included) are desperate to get one and they're in scarce supply right now. Could be anything from $50 to $100. Sorry to be the bringer of bad news. Hope this helps and good luck!
Man I guess consoles went down a little bit, I'm used to seeing them at $80 but there are some here (eBay) for $50.
Flash carts are about $90 new (maybe that's with the linker?) but may have developer discounts for people that have made something. You likely won't find any for sale, and certainly not for much less than that considering the demand.
If you don't have the money I'd suggest just sticking with a console and developing with the emulator. It's easier to debug, anyway!