Think about how the thing would be written, and how it would turn up in assembler after being compiled
Probably a function to subtract the funds.
So say...
void Subtractfunds(int subtractthis, int& pointertomoney) {
pointertomoney -= subtractthis;
}
Would probably look something like this in assembly (very very roughly, I don't have all that much ASM experience)
POP(EAX, pointertomoney) (Ehh, that don't look right. But I can't check it at the moment)
SUB(EAX, subtractthis)
And then it would push the new value back to memory.
Nopping out the SUB would work to stop the money from decreasing when you buy stuff.
But I'm guessing that money is server-side and the value and the buy requests are from the server, so probably not a good thing.