I suggest checking FRY’S for great price and selection, and considering the extended warranty contract.
Selection at COSTCO is OK, but very limited.

LCD should be a better value and MUCH, MUCH cheaper on electricity use. (I read that plasma could easily run over $10 a month)

WALMART has had some nice deals lately, but last time I checked the largest set was 42″. They were offering extended payments at 0% interest if purchased by 12-31, I don’t know if that offer is still on.