I use these for variable DC voltage from AC. They are "rated" at 2 to 3 amps, but in reality, about half of that is the practical maximum. If you look around on eBay or places like AliExpress, BangGood, etc. you can usually find them or similar units for less than $5/ea.
Be sure you check the ratings, many of the hits on a search will be 110/220 input modules, that's not what you want!
Search for ac-dc power supply buck converter step down module.
Here's a couple of the styles I've personally used, each of these have similar capabilities.