I'm also thinking about clip-ons and because of the crappy weather a small selection with the Dutch price converted to dollars. Seen allot of different models and types. But not all are available in 52mm.
One of the cheapest I ran in to: €139 ($188)
Clip-ons by Valtermoto: €179 ($241)
LSL Sport-match clip-ons: €155 ($209)
LSL Tour-match (high) clip-ons: €269 ($362)
Gilles Tooling doesn't have a 52mm clip-on. Shame 'cause I really like their Basic Variobar model, price from €299 ($403).
However the cheapest model of all is by Gilles Tooling and also looks nice. That's the GP Light model. Just €125 ($168)
I'm thinking of going with the LSL sport-match clip-ons. Price and looks are just right.