If i had such a collection of classics and discontinued products i wouldn't part with it easily either.
Perhaps the person in question is just price checking in case of making up a will or to be less grim just plain curiosity what his hobby has earned him or her thus far.
I can't think of any sane reason why a person would really want to part with this unless they really need money, then again if you managed to build up such a steady collection over the years have a child do you really need the money? Would be a bit of drastic end of a hobby if that was the point i would put it in storage somewhere and sit on especially the less common items and just pass them on to my kids and watch other collectors throw absurd amounts down for it.