I use a Wagner from Home Depot; the cheapest one they sell. You don't need anything but the high setting, precise heat settings are not necessary, the distance you hold your heat gun from the wood determines the heat setting.
My first Wagner lasted 20 years and only quit after being dropped one too many times, my second lasted about a year but I overheated it by holding the tip too close to the wood during heat treating. #3 seems to be doing OK, only time will tell.
I went to an estate sale last year that had at least 6 heat guns on a table, I picked up a Milwaukie that was built like a tank for $5 to keep as a back-up, it has a very hot high setting. I don't think I will have to buy any more of them.
I made a holster for my heat gun on the edge of my work bench, pretty handy to have while heating and tightening down the clamps on a bow.