Did some research to make sure I was setting the right price expectation for myself. Interestingly, it's tough to find a manufacturer that either sells a "cold weather package" as an option without bundling in a bunch of other stuff (I'm looking at you, Ford Mach-E), or just rolls it into the higher end model and doesn't offer it as an option at all. So far, the only standalone option I can find is for a 2022 Camry SE, which includes heated front seats, heated steering wheel, and heated side mirrors for $1,100. Subaru used to offer it as a standalone option for around $1,200, but seems to have rolled it into their higher end trims. The Mach-E has a "comfort and convenience" package, but it includes a LOT of extra stuff past just heated seats, and I can't find a price since Ford took down their configurator (at least as far as I can find).
I'm realizing as the Fisker Winter Package includes rear heated seats (that I don't need) and remote pre-heat, it's probably going to be closer to the $2K range than the $1-1,500 I'd prefer.