None of my listings are Plus, as I charge postage separately and have a longer handling time than is required.

This is the criteria for Plus:

Seller is above standard or top rated, item is in Aus (and return address as well), not heavy / bulky, listing has a 0-1 day handling time, accepts returns, free regular post (domestic), offers an express post option, and doesn't charge extra postage for additional items.

I'd probably charge something like 5c per additional item, if wanting to remove my listings from plus.