This was never a dedicated game, you probably know that.
If you don't get any bites another option is to find any six button Jamma fighting game for sale in your area with a 25 inch monitor, then go to Ebay and buy a SFII marquee and PCB plus harness for the extra two buttons, spend 15 minutes putting it together, and you have a Streetfighter II.
All that stuff is for sale on Ebay right now, dirt cheap. 99 cents BIN for the marquee, harness for $15, working SFII boards for not a lot of money. That brings up a good point. Which SFII are you looking for? I think Champion Edition was the one where if you won the fight you get to play for free against the next challenger. As I recall that was the most popular version of the game. I did see a working Hyperfighting board for $100. I think that does have the Champion mode and was pretty popular.