Personally, I would keep the Antigua Winds alto. They're a pretty good sax, but they don't often bring much more than $500 used, even in excellent condition. If you sold it, you might regret it! I play both alto and tenor, and often swich back and forth between the two depending on the tone that I want. I don't know your age or level of experience, but I wouldn't try soprano until you have a couple years experience on tenor or alto. Soprano requires a lot more embrochure control than alto and tenor, and they are much more difficult to play. Rather than sell the alto, I would just start saving for a new soprano later down the road.