I think in a way flippers can and do drive up prices but the prices they drive up are on the fixer uppers, People have an old bike to get rid of and they check CL and see what a fully tuned, ready to ride bike like the one that's been leaning on their shed for ten years is going for and the bike they thought was worth $10.00 is now worth $50.00.

There's still deals to be had for sure but it does take a lot of effort to find them.