Currently running two sets of rims on the RS. A set of Borbet Type T's in a 17x9" +35 flavor and a set of Enkei RPF-1's in a 17x8 +35mm.
Fenders have been massaged to fit the wider rims.
Doing a search won't yield much in the RS department, and even less in the WRX department. There aren't too many manufacturers that make a 17x9" rim in a 5x100 bolt pattern. I've done some research about converting over to a 5x114.3 bolt pattern (SVX) but haven't had time to fully pursue it. Plenty of options in a 5x114.3 (BMW, etc..).
As pointed out above, Fikse, HRE, and a few others will make you anything you want. Bank on ~$1k per corner depending on who you go with.
Best of luck with your project.