I can tell you why to purchase a mattress ANYWHERE else... because Sleep Country will make it impossible to ever make a warranty claim. Reading the reviews below I can see we are not alone.
We purchased from Sleep Country what we thought was a superior mattress set paying more than we had budgeted (what we considered a premium) in order to get the support and life from our mattress. My back had been bothering me and we felt we had no choice to but spent what was to us a considerable amount for a quality, name brand (Serta) premium mattress. That was in June 2010. Additionally, we purchased the extended warranty to be sure our investment would be protected.
Only two years later (bed carries a supposed 10 year warranty), there are sizeable “indents” where our bodies lay on the bed. We started their warranty purchase and they are 1.5 - 2 inches deep. Neither of us are overweight either so that certainly wouldn't be the cause (just in case there's another excuse we hadn't heard yet).
The mattress was delivered and setup for us with the current frame. As a matter of fact, we described the frame to the saleman who then helped us select the appropriate boxspring to fit. There was not mention that if it didn't have a fifth leg the warranty would be void. We would of course have purchased a new frame if we had been told that - for crying out loud we threw good money after bad purchasing the extended warranty!
We are beyond disappointed and will make sure all our family and friends are aware of our experience and make sure they go anywhere BUT Sl;eep Country when they purchase their next mattress.