At the wide tfov end high quality EPs get very pricey. I want to try a 28mm UWAN which sells for a bit over $400. If it's as good as everyone says (except Mike
), it would seem to be the best bang for buck for an f/5-ish, and it's an ultrawide!
30mm Stratus / Scopos is the only cheaper option I know of that should still work fairly well. Saxon are also meant to be importing their versions of these EPs.