1. Create an additonal formula for Lowes items -- go to Settings --> Marketplaces --> Ebay --> US --> go to the additional formulas section, select Lowes and type in (-(vendor_shipping)). Save settings.
2. Remove Override Formula from all Lowes items --> Set your grid to view 1000 items per page --> Use the 2nd filter on the page and select Lowes as the supplier. That will filter out all Lowes items so you'll have up to 1000 Lowes items on page 1 of your grid. --> Use Multi Item Actions --> Select All on Current Page --> Multi Item Actions again --> Remove Per Item Formulas from Selected Items. ---> Then Force Reprice Selected.
3. Repeat on page 2, etc. if you have more than 1000 Lowes items
4. Give them some time to update.
So this will ultimately use your default selling formula to create a selling price and then subtract whatever is the cost of shipping from that selling price that is created. Example, if the shipping amount is $5.99 and your default formula would set your listing price normally to $29.99, then once your additional formula is applied, your selling price would change to $24.