"Hey, do you wanna sell your bike?"

Late last night, I was asked to go pick up a gallon of milk at grocery store on my way home. I was on my very old (20+ year) mountain bike and didn't have a lock with me. Since the store was mostly empty, I decided to just take it in with me. I walked into the store, got my milk and went to checkout.
As I'm standing in the checkout line, the guy in front of me bent down to take a close look at my bike (which made me a little uneasy.) He stood up mumbling, "...1 inch tubing..." and asked if I wanted to sell my bike. Curious about why anyone would want an old junker I asked him why. He said to checkout kingsmotorbikes.com. In looking at their site, it looks like it could be a fun project and would be handy (if I didn't already have my beloved motorcycle.)
I probably won't do it anytime soon, but if you or someone you know does, I'm curious to know how well it works!