I always ask "what's your best price?" People who deal with me know if I am asking that I am very serious. They also know I bring cash, dont pick the game apart for small issues, and if you are selling it for 3500 and tell me 3200, I will give you 3200.
It works the other way with me too. If you call me and ask best price and I tell you 3200, I wont renegotiate once you inspect the game.

I do the same thing. If someone has a game I want but its a 5 hour drive, I always try to make it worth my time and get as many games as I can. I also know when to back off. I will never ask about games in the background of an ad or that are sent to me. I will ask if they have anything else to sell. You need to let them think they offered the game. You can come off as pushy and they might get salty towards you and ruin your chances on buying anything.

My go to response is always " That's a solid down payment, you can pay the balance on pick up." I usually get a laugh which helps move things along.