Amazon require list price/rrp when listing product. I sell used items merchant fulfilled and don’t have this data.
Shall I just put “0” for this or shall I just equal it to my selling price?
For used MFN items, the list price field is basically meaningless and most sellers just skip it entirely, because it’s only relevant for new retail items where the manufacturer has an official RRP.
Putting zero can trigger errors, and putting your selling price as the list price defeats the purpose because it stops Amazon from showing any “you save X%” messaging, but it won’t hurt your account.
The simplest and most common workaround is to leave it blank if the flat file or interface allows it, or, if Amazon forces you to enter something, put the same number as your selling price so the system accepts the listing without creating a fake or misleading RRP.
It won’t affect Buy Box or account health, and for used products Amazon doesn’t care about MSRP accuracy the way they do for new items. Most MF sellers just mirror price = list price and move on.