The thing is, when someone can buy a new bike from Performance for around $300, it's tough to sell a decent bike with DT shifters for anywhere near that.

My flipping days are behind me, except for the occasional high end bike that is a diamond in the rough. Last bikes I sold were a Colnago and a Waterford. Doubling your money on a $600 bike with modern components beats scrubbing rust off a Schwinn/Raleigh for a $100 'profit'.