I haven't bought anything from them recently (although like Billie Dee, I have quite a collection) but I can speak to their excellent customer service. I accidently ruined a couple of their sets because of the way I stored them and mentioned it on a thread here as a warning to others not to store their stamps that way (the thread was about the old metal DVD-style cases).
The owner of KSS happened to see that thread and replaced the stamp sets at no charge to me, even though her company was totally NOT responsible for what happened to them. That spoke volumes to me about how much she cares about her customers!