Ian at BikeRev makes a great product for a very modest cost. Best of all, his trailers can lock securely in addition to being virtually waterproof. I've got one of his regular trailers, and then I've made several versions using his trailer kit. It's a pretty bombproof trailer and tows great. After several Burleys, one BOB, and a couple of Wikes -- it's the trailer I've kept since day one.
Still like to try an Extrawheel sometime though...