In my experience in 2011, Nirvana Seed Company was a complete fiasco. Shipping and customer service procedures are terrible. I ordered 5 shipments of seeds from Nirvana in 2011 - three arrived. Nirvana ignored all e-mails for two solid weeks (as our short Southwestern growing season started, I was stil arguing with Nirvana about when they would ship my seeds).
I got some good seeds from Nirvana, but I also got some really bad strains too. Nirvana has a super-fucked up business practice of "cutting you off" if you complain to your credit card company and ask for a chargeback (I have never been denied a chargeback against Nirvana): if you charge back a credit card charge, Nirvana sends you a nastygram informing you that they will no longer do biz w/ u and blah blah blah (just use a different e-mail address next time). This is a super-fucked up business practice because basically Nirvana's attitude seems to be "our way or the highway".
Nirvana seeds are inexpensive but only half of the strains i got from them were worth a shit. Worst of all, Nirvana's amateurish delays caused me to lose a whole month of growing season.
I buy Dinafem seeds from Attitude now. Get the insurance too.