All of this is assuming the seller actually cares about the pin market. If they do, then this whole conversation is moot - KK is not gonna get them for a dime less than $5K.
I assume nothing. Sales history on pins is NOT reliable info. Pricing is all over the place. Within the past year I've seen nearly the exact same FP sold for $1000 and given away for free. No shit. Right time, right place, right buyer, right seller. They're not commodities, let's not fool ourselves into believing they can be priced as such.
Personally, I'd ask the seller what they want for the pair of them. Get an idea on their needs.
"Give me an idea of your ball park price range, and I'll tell you whether or not we're gonna strike a deal here."
I ALWAYS come in low and work up. The whole mentality of 'scaring' away a seller is just ludicrous IMHO. Cripes, people haggle over a sweater at a garage sale, for cripe's sakes. I hardly doubt that a motivated seller will be 'offended' at an offer that's too low. They'll just say "no."
And it's not like these are grails for the OP. He's simply interested in making an offer.