I use Anton's and find them pretty reliable. They frequently give coupons, so it cuts the cost down a bit. They're outside of Porter Sq on Somerville Ave in the plaza w/Starbucks. Not exactly convenient to Davis, I know.

Buywithme or Groupon has had a few 1/2 off coupons for Zoots, though you have to be a "new" customer (haven't used them for the past 6 months).