Only place I know to get Seeds is the ICPS Seed Bank:

http://www.carnivorousplants.org/seedbank/seedmain.html

You do have to be a member of the ICPS (International Carnivorous Plant Society), but...

ICPS is the best source. Some nurseries offer them too, but they're more expensive.

One place to NOT go is ebay. You seldom know what you're getting. There is one vendor called Seedmart or something like that. It is the same vendor that operates as Hirts selling plants. They do HUGE sales (just look at that feedback for the seeds alone!) but they list things like nepenthes seeds without any mention of what kind of nepenthes and they offer seeds for plants that they do not have. I don't know if they get them from places like the seedbank and hang on to them until they sell, but I would NOT trust their seeds to be viable.

Oh, don't order their plants either unless you can go to the greenhouse and select them personally. The quality is very hit-or-miss.