i was buying a prolite and searching around for the best discount, i noticed many stores do not apply discount/coupon codes to thermarest/cascade designs, like western mountaineering. rockcreek.com is 15% off everything i believe, code ' WELCOME443 ' add to it the extrabux, fatwallet, or mr rebates 4-5% rebate.
if you dont need it now you might be good waiting.
oh and basegear.com is 20% off for just joining mailing list, not sure if it applies to thermarest
also one on gear trade from backcountry, brand new just without tags