I’d like to add: down comforter.

Last winter, a king size at IKEA ran me ~$100*. The cover was additional but less than $50 (on sale).

* All cotton, shell. Something not all cotton would be less expensive.

The damage from a frozen water line in your house can be a lot more than $4000.

We had them when I was still a kid in the sixties and I did not like it at all. Jumping in a warm bed is nice but leaving it on during the night makes you wake up all sweaty in the middle of the night. Even on the lowest setting.