Well I think every diablo-cheater cheated his money by writing directly into the memory the value of coins stored in inventory ... but money in Diablo can be cheated in other way - by cheating the ammount of money you want to DROP on the ground/into inventory ... you can make lot of money even during online playing on battlenet. When you want to drop any ammount of money you drop money of the same value everytime and this money isn't duplicate of the original (!).
HF