My search results (run on 3/31/07) are below. Here are the parameters I used: 1400+ square-foot; single-family; active MLS listing; $300,000 or less. (See here for an explanation. I exclude condominiums and townhomes even if they are listed in MLS as "single family.")
South Austin (MLS areas 6 & 7): One. (There were three last month.)
North Austin (MLS areas 1B, 2 & 4): 21. (Up from 18 last month.) Almost all are in the Crestview, Wooten, Allandale or Highland neighborhoods. There are none in the rectangle bounded north-south by 45th and Town Lake and east-west by I-35 and MoPac.
East Austin (MLS areas 3 and 5): 42, down from 48 last month.
See you next month.