In my experiences with BuyersAssurance (also probably applies to its clones), they will take any coupons and/or promotional gift certificates (like Amazon promos) off of your pricematch. They also figure the cost of shipping against you.
Although I still have gotten far more than my initial investment back, it sometimes pays to know all the factors that they will assess against you.
Also, the CSRs at BuyersAssurance have no real knowledge or power. Anytime that I had a real issue that needed to be addressed, I was told that they would forward my concern on to someone that could help me. They will also respond to e-mail requests for help.