I have been through a few threads about AH. And I have yet to see someone state a legitimate reason, aside from over paying for an item (sellers advantage), that CAN NOT be implemented in the Market Wards...
Ppl complain "An AH is global!"
No, not all MMO AH are global, nor is that a feature limited only to AH. Also in the future SE may connected the wards for viewing purposes. Example: you are "item searching" in UL and you can see on the list items from GRID (specified by city).
Ppl complain "too much undercutting!"
Um, AH doesn't solve that problem either!
Ppl complain "The Wards have no price history!"
That is correct... maybe in the future they will address that.
PPl complain & complain & complain & complain
And have yet to state a solid argument for AH that could not be implemented to some extent with the Market Ward.

Lets be honest. Have um-teen threads on AH can we be certain that SE will not implement a AH b/c that would undermine the Market Ward they are working so hard to establish?!