Listing a single item but offering additional identical items for sale in the item description (to avoid being charged for more than one item or listing) isn't allowed on eBay.
Violations of this policy may result in:
Limits on account privileges
Forfeit of eBay fees on cancelled listings
Loss of PowerSeller status
Note: If you want to sell multiple items as a set, your listing quantity should be ‘one’ and the description should specify the total quantity within the set. For example, if you're selling four bowls as a set, you'd indicate that this is one set of four bowls.
Instructing buyers that they can purchase additional items from this listing for the same price isn't allowed.
Why does eBay have this policy?
Single listings that offer multiple items to avoid fees can put sellers who pay all their eBay fees at a disadvantage and undermines the trust and legitimacy of eBay’s marketplace.