Plutonium-238 can only be made via Uranium-238. Per the Seaborg process, you must bombard U-238 with deuterons to get Neptunium-238, which then further decays into Pu-238. The Pu-238 then decays into U-234 with a half life of ~88 years. U-234 has a half life of ~200,000 years, btw.

It is very unlikely that the production of Pu-238 would cost less to produce than the container and the apparatus that harvests the energy.

Let alone the issues with the waste products of U-234 hanging about in the kitchen or basement. If you think climate change is bad as is, add in what people will do when faced with surplus uranium waste removal costs.

https://en.wikipedia.org/wiki/Plutonium-238

So only six figures for fridge? Sounds like a good deal.

> the costs would be much closer to the materials cost

Which is? Not cheap. And it's not like you can buy in any corner store.

And no, while an "economy of scale" would make it cheaper, it doesn't mean it would be cheap.