I think this is a good idea. God did not put his church on earth to keep expensive artifacts. If they can use the money to further His work, that is better than to simply give people the pleasure of seeing an old book.
Old South Church selling their "Bay Psalm Book" is like the town of Plymouth selling Plymouth Rock to the highest bidder. They're one of the oldest Congregational (though now UCC) congregations in New England.
Of course, they long ago abandoned the Pilgrim's stern and rockbound beliefs for trendy "inclusion", and therein lies their problem.
Their embracing of the usual mainline "inclusive" nonsense drove off traditional members, and the various minority groups they hoped to "outreach" to aren't contributing, although they're happy to take handouts. When you have an "interim minister" for 4 years, you are a dying congregation - and it looks like only a couple of hundred people attended the vote.
So they are a semi-abandoned urban church with no congregation to speak of and thus no money for upkeep. Add to that an aging building (1870s) and deferred maintenance, and they have a big problem.