I don't see anything that just pops out as must have for me....
I recently sold my Virtual Boy and 3 games for about $100. I could have gotten $200 or more, but the poor little guy was starting to have issues with the graphics glitching so I let it slide for a bit less. I didn't play it and it took up unnecessary space in my storage closet.
I also sold off my 3 NES and dozen games, gun and 5 controllers for around $140. I hadn't tested any of them for the past 10 years, but they all did work before I boxed them up.
Anyway...while his collection certainly is impressive, he'd make a lot more selling them off in lots and not a large bulk. Most collectors aren't out to have what he has in it's entirety. I know my older brother - at one point - was on a mission for collecting NES games. He wouldn't be interested in anything else in the collection.
I know my younger brother really wanted the Virtual Boy I had, but with it starting to fail he passed on it. He may be interested in the Virtual Boy set, but nothing else.
This is like selling off a pre-built PC. Sure, you might find someone to buy it, but not for the price you want. You're better off piecing out the computer and you'll make more on it.