A buy in bulk option like the new 8.3 WoW AH interface.
If there are stacks of herbs for at 9g, 10g and 11g you select all. and buy them with one transaction. Just like the standard interface.
On the same note, a buy all button for one stack would help a lot.
at the moment you have to type the number indiviualy, e.g. there are 321 sea stalk so you have to manualy type in 321 and then buy. a buy all button would eliminate the typing. Or a max stack button wich fills the panel for you