Before the last patch I was working a lot with the prices of my last auctions, would it be possible to add that tab or something similar?

Is this to view while posting auctions?

Find this in alpha 433

I'm not sure what you mean by this, so my apologies in advance if my comment is inappropriate.

When reauctioning an item I would like to see my last auction price. I'm assuming it failed because I was asking too much. Maybe this isn't possible with WoW.

Rift had a far superior auction house. Instead of mailing your failed auctions, they remained in the AH and you could either reauction them or claim them. I suppose that made it easy to show what your last asking price was. It also showed a graph of price history. Nice stuff.