I started using getters and setters, but got into the problem that at some specific situations I did not want the value to be modified for formatting (like when I wanted to do some addition and calculations on the raw values).
What I ended up doing is taking my db values (stored as decimals) and passing them to a helper function I wrote to format it. I have a helpers file loading with composer with various little functions like this one. So I just end up passing the value to it and it comes back formatted correctly using the money_format php function.
So far that is what has worked best for me, but always on lookout of better alternatives if you find one.