While I was playing today, I went to the Auction House to buy some mats for my hungry seraphynx and basicall it came down to "I want to buy a 5* mat", *clicks on "Sort By Stars*, "But I also want it to be the cheapest possible", *clicks on "Sort By Price"*.
All jokes aside, is it not possible to make maybe a drop-box option that lets players look through specific sections. Example, have the option to choose, from the Stars tab, to look only at 5* or 3* or whatever. Or in the Prices, show all the items between prices written by the player as a minimum/maximum amounts. With that you could also add 2 sorting systems, say have a primary one and a secondary. Example, have the primary sorting on Stars so it looks the 5* and have the secondary as Price so it searches from the cheapest to the most expensive.
I'd say if those 2 things make their way into the game, it would make looking though the AH MUCH easier (as sometimes you may end up on 237 pages of results when you only want one thing)
Just search the mat name and set it to by price.