The best deal I ever got:
Circa 2005, I was a regular at one room I'd stop in after my dayjob. The owner told me he had just bought a 4 point Black Boar from a guy for $600. I looked at it, and said I'll give you $900. He thought a minute, and said yes. I had it refinished by Proficient and sold it a couple weeks later for $1500.
The cue came in a 2x4 Its George plain black leather case. I used the case about 15 years, then sold it on here for $150 or so. It was well used, but still sold easily. Funny thing about that being a "2x4", it really only fit 2x2 unless the cues were loaded in a weird and specific way, which I never did.
The seller was a former player that quit pool entirely for about 15 years. That day, he took the cue from the back of his closet and brought it to the nearest pool room to sell it for $600. He didn't know that BB, or Its George, had increased/retained their value, as he was completely out of the game. He was happy to get $600.