I am using hotcakes entirely as points based with the only use of US dollar sign potentially for shipping and tax. Ideally I would suppress the $ by line item/where used, but if not possible then anywhere the $ shows up.
Do you still intend to have a checkout process?
In thinking through everything, I think the best way to start is by modifying the views that aren't the Cart and Checkout first. Those will be easiest. You'd want to visually hide the pricing using CSS, and add new elements to your views that duplicate what the pricing was doing, but modify it server-side in the view itself to remove the dollar sign. This should be as easy as using the number formatting methods built into .NET.
You do it this way so that some of the client-side logic still works, but you're showing what you intend to visitors.
The Checkout and Cart will be a bit more trial and error, I think. The Checkout especially has dynamic aspects to it that will make what you want to do challenging, but doable. I just can't tell you the specific steps in those cases.