It really is good business.
I find it rather shady. Probably why I drive a vehicle till the wheels fall off and then and only then set foot on a dealership's lot.
Tell me what you will buy my car/gun/whatever for and tell me what you will sell your car/gun/whatever for and let's make medicine.
Why make something so simple so complicated?
For me, there are two prices on everything ... FMV and what I want for it.
If I'm ready to move onto something else, I'll price it accordingly.
If I have something you want to buy and I'm still "attached", I'll price it accordingly.
I won't advertise two prices.
I guess that's just me.