I have a big huge available list of Game Boy Original titles. All game cartridges have plastic cases. All boxed titles have plastic box protectors. I collected everything at one point and have 400+ titles remaining.
I'm slowly sending them to eBay for collectors that want to buy them quickly, but will also consider offers and trades. I'm only looking for PS4/Vita games and will check lists. I accept PayPal, PSN Cash, Amazon Credit. Some titles have shipped prices listed, and anything not marked I can give you a price on.
List is available here. Click the GB (number of titles left) tab at the bottom left side to view the list.