Depends...do you want it all the time...or do you want to pursue a binge and cancel policy?
If you want it all the time, some of the 3 year deals are the cheapest, HOWEVER, there is no refund for that plan, so MAKE SURE your tv or devices will run the service (right now, Amazon products will not, as an example).
If you want it on and off, the cheapest way will be to let it release, probably get a free week/month plan, binge, and then cancel til the next special...