The Vendor Price Diff field is an advanced option available on options settings pages (Inventory > Options > Option#) that can be used to specify the price you will pay a vendor for the cost of a product, based on a specific option.
For example, if your cost for a series of t-shirts is $5.99 per t-shirt, but $6.99 for t-shirts that come in red, you can enter a value of 1 into the Vendor Price Diff field for the t-shirt's red product option to reflect this increased charge.
Using the Vendor Price Diff Field
This field can be found by going to Inventory > Options, and clicking on the Option ID you want to edit. The Vendor Price Diff field is under Advanced Info.
Note that it should not be used in conjunction with any product/product options combination configured to use the Inventory Control Grid feature.
Also keep in mind that the product must have the Vendor Price field configured for this field to apply to a product when an option configured with a Vendor Price Diff is selected.
The Vendor Price field can be found within the product settings under the Vendor Information heading.
The Vendor Price Diff field within a product option will only be applied to a product provided that the product is configured to drop-ship from a vendor via purchase order and will only be displayed within a purchase order.
Furthermore, this price difference will not be reported for product's cost of goods sold within the Reporting page.