I need some help with purchasing a bed and sheets.

I’ve pretty much decided what bed I want, it’s one of those Sleep Science Temper Pedic Mattresses.

I was told to get some good sheets for this type of bed because it holds in a lot of heat. What thread count is good for the sheets and comforter?

I’m buying from a Costco, so the level of customer service isn’t always the best. Any help would be much appreciated

Thanks!