Are the rare handheld games valuable?

[KitKatty5]

If you own any of these handheld games, have you ever looked up their value? I didn't know they made handhelds for these games, so I'm guessing that they were somewhat rare? I could be wrong.  I'd love to know the pricing on them, though?

[TwitchisMental]

Doing a quick search on price harting shows Enter the Gecko for GBA to be around 30 for a complete copy.  Deep Cover is only around 10.  

[Nomad]

I do not own any handheld games or retro consoles. However, I have seen them listed on eBay or Facebook Marketplace for a really high price. By the way, I am not a collector.

[Ravenfreak]

Yeah the Gex games on the GBC aren't too expensive. They're certainly not as popular as the Pokemon games.