The NA Rock Garden Society now has its seed list posted on-line. If you have contributed, you can get 35 pk. for $15, and 25 if you have not contributed. Many of these seeds cannot be found in most commercial locations.

It is worthwhile to join just to get the seeds, even if you don't go to meetings (the Chapel Hill group has great speakers!) and even if you don't have a rock garden, which I don't. I have had good luck with germinating most things. My problems come from growing them out to a size large eough to swap or put in the ground! I am now trying just putting many of the seeds directly in the ground and see if I have luck there.

Here is a link that might be useful: NARGS Seed List