I am sure this would be fairly easy to do, but instead of me hacking a version I have thought I'd make the request here for a future version.
1) In the backend admin in the product list tab for orders where it has item name, price, quantity I'd like to have an additional column to enable the manual entry of a discount per item that can be left blank - i.e. no discount or can be a percentage, e.g. 5% discount.
2) In the Products list have a discount column for specials for each item that will be applied to those specific items automatically when ordered, the front end will show the original price with a strike through and then the 'special' discounted price. In the backend the price shown is the original price and then the discount value applied in the new discount column as per 1) above, this again can be over-ridden by admin if they want manually.
3) A whole store discount field where every product is discounted like when your having a sale - again like 2) the products original price is shown with a strikethrough and then the discounted price is shown. Again as per 2) and 1) the discount can be over ridden in the backend by admin.
I guess my last question is how long could it take to have this feature added as part of the QuickCart system by default, if it will be a long time I'll hack my copies and add this myself - I could then share it back here :).