Hi again! Yes, heating jackets are expensive, so I use a low tech version of hot water bags. Maybe start with those since they are cheap and see if heat helps you before investing in a jacket?
I will lay on my stomach and put a few on my sorest areas in the morning and night and found that often helps calm and (hopefully) prevent flares. I love Fashy brand. They are super durable (no leaks) and don't have a chemical smell like many other brands. I even lay on them sometimes and they have never opened. I know that's risky, but I like living on the edge
If you do end up getting one, I recommend also buying a knit cover for the bottle. It'll help prevent burns (you can place directly on the skin like that) and is much more comfortable to the touch.