Leatherface,start by asking around work.. or friends, relatives..
Folks Always have bikes sitting in the garage that they no longer want to ride, or wanna trade & upgrade.

You'll wanna start it up, check for wipe-out marks, loose chains, rims aren't wobbly, goes into every gear, preferably ride around the block.
Best thing is they'll prolly throw in all their gear too! helmets, etc.

Bike maintenance is relatively easy too. Worst thing for me is rear tires.. every 6-8K miles.. ouch.