Can I add an add on price for an accessory to a listing

[mam98031]

More details please.  This isn't enough information to accurately answer your question.

But lets say you have a purse that has a matching wallet.  You want to list the purse and say you have the matching wallet for XX $$ more.  The answer would be no, you can't do that.

You would need two listings, one for the wallet and one for the purse.  Or you can list them together for one price.

Does that help at all or am I way off base?

[bigdeals.etc]

You'd have to create a separate listing. But after you create it, you can link the listing's URL into the body of your primary listing thru HTML. It's not exactly what you are asking for... but you can cross-promote this way. Just gotta make sure the cross promotion is to another ebay listing and doesn't point to another selling channel or site.