Developed by Bit and myself on Nostalrius forums: https://forum.nostalrius.org/viewtopic.php?f=63&t=21102
Buillt on Nimeral's backport of Zirco's Auctionator + many extensions and a lot of polish have been added making this indubitably the most useful Vanilla auction house addon to date.
Aux adds two tabs to the traditional auction house layout, Aux Sell and Aux Buy, which make selling and buying respectively a much more streamlined experience, automating a lot of the annoying little tasks involved in managing your auctions and providing you with much better information to base decisions on.
The Aux Buy panel makes a multi-page search for you and lists all items with the most relevant information sorted by unit price. From that list you can select all the auctions you want to buy and after your confirmation Aux then makes another multi-page search, picking up all the selected auctions in the process. (There is no better way to do this with the Vanilla API, but it is still vastly better than the default browse tab). At the end you're presented with a report about what has been purchased (sometimes the auctions will already have been gone or the search may be interrupted by closing the auction house or switching tabs, resulting in not all auctions being purchased). Charges of items are treated the same way as stack size, making scammers who put them up with one charge very obvious (see screenshot below).