Hi Mark. Cool...you don't have to spend a fortune. There is no "best." All sorts of good ones. I am just starting to experiment myself with single drivers so i'm not the one to make final recomendations but www.mulhuish.org/audio/index.htm is one of the better single driver forums I have found and lots of experience there to bounce questions off. Don't seem to be to many lowther/single driver effeciency folk here but I may be mistaken.
I agree you do not need 30 watts. Less is more.
what Lowther driver do you have?
I remain,