I recently found the leather wrapped flat bottom steering wheel out of a wrecked 2015 Subaru WRX for relatively cheap, at least compared to the oem price from Subaru. I would have liked the perforated leather of the 2015 STI but it still feels much nicer than steering wheel that came with my base premium XV(If I'm honest I'm not really sure what it's made of to begin with. I had to buy the back cover for the CVT WRX and the silver trim off the spoke that the limited XV comes with, but the airbag, media controls, and paddle shifters that came standard with my car fit just fine. I used this tutorial off a Forester forum from a guy who switched his to an STI wheel. (http://www.subaruforester.org/vbulle...ter-sj-371425/
The airbag was relatively tricky to get off, in the tutorial he(Or She) mentions having to push the three pins that hold the airbag in place to take it off. The one on the left and bottom ones are pretty easy to get to, the third one on the right you have almost no room to get in there so you kind of have to play it by feel, I practiced on the WRX wheel before hand.
In the tutorial the guy didn't have to use a steering wheel puller, but my wheel was stuck on pretty tight so I ended up buying a puller for about $15 at a local Autozone.
Also the three buttons on the bottom left don't actually work as I don't have a MFD(I'm looking into remedying that soon) like in the Forester or the WRX. So I just used some electrical tape to hold it to the wheel so it doesn't make any noise for the time being.
Let me know if you have any questions!