Mea Culpa,
Yes, the ones in your pic are STi V5. Mike Shields does carry them.
And AV Sports is indeed in Arizona, and the seats you're talking about are European-market WRX seats, pictured here in my attachment. They were selling them for under $600/pair. Yes you read that correctly.
If I were you, I'd go with those. STi seats are nice, but pricey!!!
The only thing I hear is that those WRX seats sit a little HIGHer than stock. They're take-outs from the new bodystyle, which has a slightly different seating position, that translates to a somewhat higher seat when placed in the GC8. Kind of the opposite effect from what's needed really, in an Impreza. It's a very high-seated car.
However..... if you can find a pair of the OLDER Euro. WRX seats, from the GC8 bodystyle, that should be a better setup. I just can't find 'em anywhere. They were black and grey.
-S2-