To show you how the add spell is broken, cast four times on the same target - instead of 40 units, I was getting 150. I tried this on two separate computers to make sure it wasn't a bleed problem on the first. The take spell was actually taking away 10 before adding some new amount. If you want to get a better idea of the number sequence, cast add 4 times on the same target and then cast take 4 times on the same target and you should end up with a couple of thousand and some.
That's why I said they were both broken.
I would think that it would be easier to do this kind of thing through utility and logic block events in the step event. DC would check every step on the current time and when it's a new day subtract one from each member of the party. The problem with using a coin slot is that you can not buy food in a store, you have to "fake" it with a a who pays event.