Show and hide part of collection

Hallo,
i have an Euro coins collection . Part of the collection are coins from “micro states” like Monaco and San Marino. In usual swap offers i do not want to offer these coins for a swap as they are more valuable and rare. So i do not mark them as swappable..
But sometimes when i do offer a swap and i want to make it more attractive, i want to show these coins as swappable.
These coins are on high demand and i prefer not to reject swap offers.
What would be the best and easiest way to show certain coins for some swaps and hide them for another ones?
Thanks
Ludvik