My sister in law got a new Yaris - she is very happy with it - she has seen upper 30's to low 40 mpg.
You may also want to look at a hyundai accent. It starts at $10,700 and decently optioned at around $12,500. Runs on regular - mid 30's mpg.
You may want to spend time on
www.fueleconomy.gov as you can find the epa fuel economy #'s and then people also submt their real world #'s.
The accent has seen 35-40 mpg
My wife has an 02 elantra, my brother had an 04 and 06 elantra. All cars have seen high milege and still get in the 30+ mpg range