I got the "Aroma Season" mask through Amazon a few weeks ago, and it's been great so far. https://www.amazon.com/gp/product/B07P76NG3C/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1
I looked over the reviews before purchasing. Some of the Amazon reviews have commented about short life span. I went ahead and took the risk for $30. (Some of the reviews noted successful refund or replacement for dying units.) Other reviews suggested it didn't get hot enough, but I haven't found that to be a problem. It has 3 heat levels (low, medium, high) and 3 pre-programmed durations (20, 40, 60 minutes). I can tolerate the high level, but just barely. I found the medium setting works great for me.
There are other similar plug-in options on Amazon. Just seemed a lot easier to me than the microwave route.