Shadow Hearts II: Abusing Shop Cards for Fun and Profit

As soon as your shop card reaches 40%, you won't lose any money. 40% and a profit of 20% on the 50% sale price are the same (trust me, they are).

So, when you reach that point - usually in the Hermitage, when the guy in the white suit shows up near the save point with shiny new weapons - spam points. Buy at 40% off, sell at 20% extra. Then, when your points card levels up again, you can make a profit. Buy at 50%, and sell at anything you like (20% is much, much easier than 25%, and will probably be quicker). Make about 150,000 to cover the price of the crests you can buy before finishing Apoina Tower for the second time.