New class of binding; Mailable, not sellable.
I’m not sure I like the idea of mailing Super skins, since I assume you’re speaking mostly of Tribulation Mode skins, since the others are all buyable from the TP. And Tribulation Mode skins are meant to be a sort of trophy for beating Tribulation Mode itself, so being able to give those skins to others would sort of completely defeat that purpose.
I would support this sort of option for other items, though, certainly. I would love to be able to give away some of my surplus Twisted Shoulderpads, for example. Or perhaps the ability to give away some of the account-bound minis (like the ones sold in 3-packs for instance) so you could, say, buy the Super Mini 3-pack and give away one or two while keeping the other.