Googling for a link showed this might cost a bit more than I realized. If you have an IKEA near you, they have a number of budget friendly options. I bought a lightweight down comforter there about 10 years ago. It’s nice, but I prefer the down alternative (Martha).

Edited to add— don’t buy the cheapest IKEA inserts or you’ll be sweating again. Learned that one the hard way.

I have one from the Martha Stewart line that’s 15ish years old and has held up great. I live in San Diego and am happy with in through fall, winter and spring. Summer gets too hot and I normally just use the duvet cover without an insert.