Oh, I forgot to address the original question of the thread, lol.
Anyway, the deal at Best Buy discussed above by horrofilmkid is a good way, although I can never find those things at the stores I frequent.
I have never bought one before although I have 2000 points with a lot more coming soon. I got 400 from that Discovery Channel Futureweapons promo (should have gotten another 400 but the code did not show up), I got 1600 from Gaming Lagoon and will have another one any day now, and I am almost halfway to one on GameTrailers.com. That should take like a month or so.
So what is my conclusion? Buy at Best Buy if you can do that deal or even if you cannot just use your Reward Zone card and at least get something out of it. It is simply down to your preference. Have fun!