If you want to learn to drive get a tag. Most shifter drivers I have talked to that started in a shifter agree they would have become a better driver faster if they would have started in a tag kart.
Also if you just want to get out and run laps look at the Rotax. Fuels savings alone will add up quick. I can run all day for just $12 in gas. Being able to run pump fuel and a lower oil ratio then other engines makes it very easy to go out and run lap after lap. Not to mention the longer times between rebuilds.