Meh.
I looked up tires for my Corolla (195/65R15). I could get some Michelin HydroEdges from these guys, at $94 per. Add another $9.66 shipping for each tire to my door. Add another $10/tire average to have them mounted, and I'm at around $115 each installed.
I'd rather go to Sam's, pay the $111 each, plus $15 each to install, or $126 each installed. To save about $10/tire, you get unknown service after the sale, you get to pay for any flat repairs that you need in the future, and have no road hazard protection, if that's important to you. If you happen to get a bad tire from the set you buy, you've got to wait and ship it back, etc. Not for me, not for $10/tire of savings.
Now, if they had the Michelins for half-price or something...