A talented seller will look at both: supplying what a buyer needs in order to maximize their profits. Long term, both go hand in hand. Sellers who don't understand this get LESS. Sellers have no obligation to sell things at below market pricing, just so someone can get a deal.

+1 Some of my part outs make no sense as a complete bike. For instance, I picked up a Batavus Professional (nice bike). But it had some shortcomings. Did I mention it came without wheels? And the Campy Triomphe derailleurs, shift levers and brake levers were all gone, replaced with Shimano RSX STI (ugh). So what remained? The original Triomphe seat post, pedals, crankset, bb, brake calipers, nice Batavus saddle, etc. I faced a choice: spend some serious $$ rounding up the right wheels, derailleurs, and levers, or part it out.