If you can't find a mechanical keyboard for under $5, you're doin it wrong. I find them for $0-3 all the time, I'm also happy to pay $300 for the right one that someone else found for $1. So go find the right one and I'll give you $300.
If you can't find a keyboard, find something else or do something else or sell something else.... if you're motivated you will find one, if you're really motivated you'll find 50. Handouts to someone who won't take the initiative to help themselves does no one any good and frankly chaps my hide. Enjoy your rubber dome or get off your tail and do something instead of whining about the injustice of your situation. A situation that is pretty far from dire.
Give me 2 hours in any city and I guarantee I can come up with a mechanical keyboard. Walk into businesses and ask if they have any really old computer junk you could buy, talk to your school, talk to your church, go dumpster diving in the right places, get creative. Or just call a temp service and work half a day and buy a proper keyboard. Over 18? Donate plasma. Under 18? Mow a lawn or shovel snow.
Step 1: Acknowledge you are begging. Done, good job.
Step 2: Fix it.
Now get your sorry excuse for an ass out there and show me your keyboard face you sissy maggot!
EDIT: Go do something worthwhile to make some cash and come back when you have, then I'll give you a ripping deal on a Model M or some other Mechanical keyboard that's good enough to make you fall to your knees and thank the heavens you're no longer a lazy freeloader and you've actually accomplished something other than feeling sorry for yourself.