Cash is king.

Someone told him "I'll be there in 15 minutes, cash in hand" and he took it.

I always tell potential buyers "Bring a truck, Cash and take home a beautiful game"

If they say "I'll look at it tonight, then come back this weekend with my brother-in-law's truck" or "I'll come out tonight and give you a deposit, then I have to go scrape up the cash" I just tell them that I'm calling the next person on the list. I don't have time for flaky-ness.

There is probably nothing you could have done.

Every pin someone puts on CL gets 15-20 calls instantly, sometimes many more.

Even if you agree to come tomorrow at 6pm and buy it, someone will call and offer $100-200 more and say that they will come get it right now.

Pinheads are insane, they buy any and every game for sale locally, even if they never play it - just to fill their basements.