It depends on how handy you are. Here is a link to a DIY. Check it out and see if you think you can hack it:
http://sites.google.com/site/mikefocke2 ... hetop-adiy(With this writeup and other miscellaneous posts on other boards, I managed to do it myself, but I wouldn't want to do it every day).
Or you could talk to a local shop, such as Ocean Beach Boat & Auto Upholstery. I didn't use them, but they were the only shop responsive enough to send me a quote so I could weigh the cost of DIY versus having it done at a shop.