Was the TCR even offered from Giant the way you wanted it, would there have been losses due to switching out parts on a stock bike, or are we maybe talking about having a shop build it up from a frame? The latter two possibilities are certainly costly and don't qualify as buying a complete stock bike.

I think it is easier to save money on a part-by-part build at the top of the range. But if you don't specify every detail, what each part on the complete bike bought at retail has to be, it is hard to beat the economies that are offered in a complete bike. I too save money when I build a bike from parts, but I buy lots of take-off parts, my frames are either lightly used or closed out, and I build my own wheels from bargain parts I get online. Also my cockpit parts don't have to match for me to be happy.