easiest solution is to start using a golf ball cushion. Don't let the numbers get low on golf balls.
I use 3 balls mostly. switch between them for what i want to do. just as an example tho I have 63 of the level 40 titlists.
I've never bought a single one. I use these exclusively now in coin games as it plays very close to the 81 TM ball. Only .5 difference in spin.
The level 40 titlists are won in the Veteran showdowns. And even as many coin games as i play a month I still can't burn them up faster than i can win them.
the 81 TM i have 17 of but i haven't used that ball I don't think in over a year.
I have 22 others of an expensive ball type. I use that one in certain tourneys or situations. i did spend credits on those.
if you wait until they do that reward thing of spending 7500 credits or whatever , that's the best time to stock up as you get other things for the credits as well. then you have a stash. that's how i stocked up on the other two balls that i spend credits on.