Hi @diveevo-de ,
You can set the Strikethrough Price (STP) in a listing by DiscountPriceInfo field.
STP and MAP apply only to fixed-price listings.
STP is available on the US, eBay Motors, UK, Germany, Canada (English and French), France, Italy, and Spain sites, while MAP is available only on the US site.Discount pricing is available to qualified sellers (and their associated developers) who participate in the Discount Pricing Program. Once qualified, sellers receive a 'special account flag' (SAF) that allows them to apply Discount Pricing to both single-variation and multi-variation items.REF:
https://developer.ebay.com/devzone/xml/docs/reference/ebay/AddFixedPriceItem.html#Request.Item.DiscountPriceInfo Best Regards ,
eBay Developer Support