tipc
Banned
If it was an interesting enough fake, it might fall into the category of culturally interesting. But a museum is a museum regardless.
Not following this: Are you saying the "museum" offered to pay for the item but you don't want cash and rather get another item in trade? I can see how that could be an issue. Many times when things are donated to a museum it is with the express understanding they stay with the museum and not to be sold or traded away. Sometime they are temporary loans. Sometimes the museum may want to keep the "other rare thing" for their own collection and sometime it is a trust issue (they ship but you don't or vice a versa)... You get the idea. Also there is the issue of worth - you may consider your item worth equivalent to the museum's item but they may not (and in reality it may not be or it could be worth more, etc...).
Honestly if it was me I would approach it as two transactions (assuming they are willing to part with a part of their collection). You pay for the item you want plus S&H and they pay for your item. This way it takes a lot of the trust, and ancillary problems out (e.g. your item is damaged during shipping the museum gets their money back and you still get the item you wanted). If you are trading item for item it makes solving problems much harder. Of course if you can trade in person that is a different story...
No, the museum hadn't offered to pay for the items, only postage and expenses to send them (I quoted the two requests directly in my initial post). Once again I'm just looking for a reasonable trade but I am NOT just going to give them away.
As an additional data point: The Strong (hosts of the ICHEG) has a yearly budget for acquisitions, so they have paid for certain collections/items.