It's been about 8 years since I did that project, and I purchased the seats from a friend. If you were to do that same Recaro job today, I'd say you're looking at:
 $350 - $400 per seat
 $80 per adapter bracket
 $50 per seat installation
Don't forget, you'd lose your power headrest height adjust and power recline. No biggie, they just become a manual job (how often do you do those adjustments anyways?).
The other alternative is to go with Benzmac's suggestion, tho' I don't know how much that would cost. Materials would probably be (relatively) inexpensive, but the labor to install (almost a re-upholster job?) might be quite high.
Hope this helps.