Is there anywhere other than the woman in the adventures mart where I can get a Limited Wish scroll in Athkalta?

Well, if not in the Adventurer's Mart, try going to the Book keeper in Waukeen's Promenade though i'm not sure if he has one. If not there i'm 100% sure there is one in Deirex's Tower in Ust Natha.

Tip: when you do find one, try and memorize one so you won't need to find another one

i've heard rumours that dead cowled wizrd enforcers and pickpocketed nobles sometimes drop high level scrolls - it's just a rumour mind you . . .

I can confirm the rumour about the Cowled Enforcers [img]graemlins/evillaughter1.gif[/img] , though I don't recall if I ever found a Limited Wish scroll.

I don't think there is a reliable third source (other than Ust Natha and the Mart).

Well I definantly know that there are at least two in the game, and im pretty sure the cowled enforcers drop one if your lucky.