One thing you'll find with glow planes, is that smaller does not really save you any money (except in fuel usage). In most engine lines, the .40 size engines are the cheapest, or just a few bucks more than the smaller engines.

Most people start out with .40 size trainers for a reason. They are the best bang for the buck, and they are easy to learn to fly. Just look at any of the popular .40 size trainers. There are some good deals on complete RTF packages out there.