Need cheap parts
My kid wants to learn to ride a bike. He wants something with gears, but he needs to learn to ride first. We got a Mongoose beater and I stripped it to lube and clean and inspect all the pieces. It needs a seat, a post, and a pair of brakes. Is there a place to get all 4 pieces new or used uber cheap? After he learns to ride this thing for a few weeks, I am giving the bike to charity when he gets something better for x-mas. At the price of new Tektro brakes, a new seat and post, even off ebay, I could buy a new beater BMX bike for him. Its a shame not to give this bike to someone who could use it since I rebuilt it. I didn't see anything in the pay it forward threads.
SPACE FOR RENT
Try Kmart or a local second hand / thrift store. Also try craigslist.com there are tons of old bike repair companies in your area trying to sell stuff through craigslist
Ask around at local shops if they have "Take-offs" or a bin for commando repairs. You might also try a local BMX track. And if you have to put a few bucks into a bike you'll give away quickly, just remember, it's good karma.