Craigslist for an 80's no suspension mountain bike about $100. Then go to Harris Cyclery and order these
WE464 26"(559) 8-/9-speed "Brutal Beast" MTB Wheelset $144.95 pair! 
These heavy-duty wheels feature:- Shimano M590 Shimano Deore hubs (Non-disc)
- 32 DT 2.0 mm (14 gauge) stainless steel spokes
- The redoubtable Sun Rhyno Lite rims (pinned)
Resistant to small-caliber firearms!
$165 with shipping
Spend $200 on rear cog set, new cables, brake pads and derailleur / bearing adjustment and have a great, solid bike for your first couple of years!
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Be watchful, stand firm in the faith, act like men, be strong. Let all that you do be done in love.