Those heating elements are not cheap, they are probably $500 for the set.. You can probably buy one from Ebay to save you money..

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=40937&item=2461383555

I believe it is not hard to replace, all you need to do is remove the seat, take it apart, the leather is only held down by hog rings which can be removed by a plier..