Totally agree that this would be awesome. However, in FFXI you were able to pretty much stand and sell stuff from your inventory to circumvent the tax on the AH. On my server we called it the Rolenberry Mall. It took FOREVER, to actually click on everyone to see what they had and in the end you probably wouldn't find anything that you wanted or needed. So I would suggest a way to do a search much like the AH has now to see which shops you need to visit.

The tax in FF14 is not nearly as big as it was in FF11 though and I doubt many crafters would care to try and circumvent it.