The best way to estimate the value of a used bike/frame is to peruse completed auctions of similar bikes on eBay. A lot depends on the condition, size and types of components. Usually you will make more money parting out a bike and selling the frame and components separately. A frame in a popular size range eg, 54-58 cm top tube, will generally sell for a better price than smaller or larger sizes. Setting a high starting price or minimum will often lower the final selling price (or result in an unsold bike) on eBay because it attracts fewer bidders. The surest way to get a good price is for a bidding war to ensue on eBay. People often get irrational and competitive in bidding wars and pay far more than an item is worth. On the other hand, the opposite can happen if an auction attracts few bidders.