I was talking to someone at work about this today, and to Vandy and YZ250H the other day at the Nudgee practice day. That is, the value of a running bike vs a complete basket case. I know it's a can of worms scenario given that a complete bike may have all the correct parts, but then again so might a box of bits.
A running bike might need a complete rebuild in the same way as the aformentioned box of bits, but people pay way more for a complete "running" bike than they would for a disassembled bike that also needs a rebuild. Chances are all the consumables, tyres, chain, chain guides, bearings etc need replacing anyway.
As Mr Vandy said the other day, people think you're mad for starting a project with a pile of parts, but at the end of the day, if you've done it right, you should have a reliable bike that you know from back to front.
sorry Maicoman if I've stuffed your thread, it just seemed to be the exact scenario that we'd been talking about recently.