Hori Real Arcade Pro 3, aka HRAP 3.  Prices recently skyrocketed to about RM500 though, but that's still cheaper than the MadCatz stick.

If you're really interested in the SF4 stick, get the Tournament Edition, though that's the really expensive one.  AVoid the Standard Edition stick, lots of reported problems.

Do keep in mind that sticks are in huge demand currently, and not many shops stock them, so you might have trouble.  I myself got lucky an a graet forumer here sold his stick to me.