It's a good idea, thanks for your suggestions. The issue is the same as always, there're too many settings to configure. You may want to move to top every one, maybe someone want to do it daily, every 3 hours, weekly,... and change how for how long.
So to set something like that, you need at least three different values: how frequent, for how long, and at what cost. Now, repeat that for each category. Or maybe you want to offer several "packs", like hourly for 8 hours at 8$, hourly for 16hours at 12$,...
Again, it's a great idea, we need to check how we could implement this without being too complicated to configure.
Regards