Most brewers on a budget start out with the SQ14 or SP10. They are both about $50.00 shipped if you search around for a deal. Here they are on Amazon. Same burner oriface, so it's just a matter of which housing you like best:
For about $70.00 shipped, you can get the KAB4 wiht the Banjo Burner oriface, the same oriface used in the Blichmann burner and other more expensive models. This burner is wayyyy more efficient (like 40% more efficient) than the SP10/SQ14, and will easily pay for itself in the saved propane in about 10-15 batches. If you plan on sticking with brewing, this is a much better long term option. The KAB6 is also the same thing with a bigger, more rugged housing that's more appropriate for 10+ gallon batches. Bayou Classic also makes tons of models with the same oriface and different housings, but the KAB4 is the cheapest. Here's the Amazon lisitng, but shop around and you'll find it cheaper.