Yard sales can be a good source for bikes. One year I bought two Bianchi's for under $50.00. Another source can be a local Police Auction. When shopping, especially at an auction, bring a measuring tape and magnet. This can help you pick bikes that fit, and identify good alloy components when painted over. This spring, I picked up four bikes won at the Police Auction for less than $25.00. Two of them were ridable.