"Everything is worth what its purchaser will pay for it" - Publilius Syrus
I do this with pretty much everything now, except for some extremely rare items which go on the RMAH starting at $50 (recently got a Lacuni with 5.5% crit, 144 int/66 vit, already has a bid at $53). But stuff like low tier IK armor and other crap goes on the GAH starting at 20k or so ( i just add a 2 in front of whatever number appears)