A better solution is "Leather-Seat" covers on eBay. They are true replacement covers like leatherseats.com. There is a thread about them here:
eBay Leather Seat Skins
I paid $350 plus $70 shipping and can honestly say the quality is just as good if not better than leatherseats.com. Also, you can choose seat color, insert color, and stitching color for free. Several others have reported that they are still accepting $350 as a "best offer" on eBay, but this may not still be the case. If you browse eBay often, they sometimes run auctions for these sets that start very low in price.
eBay Motors: 90 91 92 93 94 95 96 97 98 99 3000GT LEATHER SEAT COVER (item 360068944857 end time Jul-19-08 01:12:48 PDT)
Just thought I would give you all a heads up!