Don't listen to @KCPenguins VGPC is a glitchy site and will often times and most times lump in loose listings in with CIb and vice versa. It will also just record the last sale from eBay or cherry pick and random sale from eBay and use that as going rate as opposed to a formula that combines listing sold prices and divides them by number of items sold.
For accurate numbers on what items actually sell for everyday type what you have into EBay. Example "Sega Game Gear CIB" then click over the sold listings so you can see what the last 100 GG's actually sold for and in what condition. Match your condition with the GG's that sold in similar cosmetic and working conditions and go from there.
I've had users see that VGPC price was glitched and that a CIB item that sells for $100 accidentally lumped a loose game in that sold for $32 and had people try and exploit that glitch in the matrix and try and convince me that $32 is the real price when the last 50 CIB versions all sold close to $100.
Had the opposite happen as well where a trader had a loose game and on VGPC a CIB listing was wrongly listed and the site is now calling this $30 game closer to $100 based on one single glitchy listing and trying to get me to pay the glitched out price That's no where near accurate.
VGPC is like Trumps scientific advisors. And eBay sold listings are like listening to Neil Degrasse Tyson explain how science really works.
Whole thing is glitchy, cherry picks what listings it actually wants to post, omits a great very many other listings and is owned and operated by the largest after market video game seller in the known universe. So beyond all the flaws it's a conflict of interest and the little bit of extra work to be accurate is totally worth it.