You can get a pair of them for $1584 here:
http://www.gahh.com/product_info.php?cPath=27_57_341_3003&products_id=1201?osCsid=5eae78be572c1a6007c262b468 067f41 a little more than you wanted, but not too bad. You can install these yourself fairly easily if you know how to work with Hog Rings. If you research their site, you can also just replace either the seat cushion (bottom) or seatbacks for under $500/
pr.
or here -
http://www.bestleatherkits.com/index.html
or -
http://www.worlduph.com/porsche10.htm#SEAT
or -
http://www.heritagetrim.com/