Keep it simple. Many folks use something like this here If you end up doing a lot of circles a more elaborate one can be made or bought
At that price range, I don't see much reason to make my own (multiple times over the years). I should just get the 200J.It is easy to make a simple circle jig. There are many posts on the forum and youtube on various designs.
Search forum for "circle jig"
Or buy a Jasper 200 jig. Should last you forever.....