is that budget just for the legs or with the head too? I must say, a tripod is actually one of those areas where you can really see/feel the difference between a $300 and $30 version.
You don't need to spend the kind of money that Thom is talking about but for a little more than what you are talking about now, you could end up with a tripod that will last you a lifetime of shooting.
Manfrotto makes some excellent aluminum tripods at a good price.