I know that the higher end electric products are well worth the extra money. The complaint that you most often hear (and these are few and far between, but they are out there) with electric infloor heating = electrical short because one of the wires was knicked during install or bent too far (whatever) and the product stops working. The higher end the product, the better the wire casings, the better made the product can be. The over all construction of the material (wires, wire casing, webbing, etc) is better when you spend a bit more money.

Personally, a cork glue down tile = warmth under foot = close to the same comfort as in-floor radiant heat...without the $500 - $1500 price tag. So long as you have a primary source of heat in the area (forced air, baseboard, etc) a cork glue down tile can be used IN PLACE OF in-floor radiant heating.

Back to topic - don't go with the cheapest option when it comes to built in electric heating systems. Cheaping out on electrical is never a good idea. Houses tend to burn down when things go wrong with cheap wiring.