If you need to set a market product price, which shows the difference between the price offered in your store and the average price of the same product on the market, use the Market Price add-on.
The add-on is free and comes enabled with the default software installation:
If it is not, you can always enable it following the general guides in Installing Add-ons from X-Cart App Store.
When enabled, the add-on adds the Market price field to the Price & Inventory section of the product details page in the Admin area, where the store admin can set the average market price on a product compared to the price in this store:
The market price is meant to show a customer how advantageous it is to order the product in this store and is displayed next to the regular one in a category product list and product details pages. In addition, a sign showing the discount produced by the price difference is shown next to it to attract customer’s attention.