To replace them and make the buttons look new again isn’t too hard, and just takes patience. This video show you how to replace worn off buttons on an 03-06 SAAB 9-3.
Replacement keys can be found on many Saab webshops, and the author of this video has got the replacement buttons here ($77 – oemsaabparts $78; skandix 119€; Ellis Saab Parts $72; Ebay $69.99; PFS Parts 104€).
Also, for the operation of replacing the buttons you do not need any special tools. Good enough is a handy tool that has in every household.
See DIY procedure: