I ask this because there is a flea market about an hour from my house.  Last Sunday, I stumbled upon this little corner of heaven while my GF was looking for flowers.  They had a megaton of stuff from the Nes days on up through a copy of Little Deviants for the Vita (the only Vita game they had).  I gave the inventory a quick glance but nothing jumped out at me.  Then, I tried to quickly google "Rare video games" but the only thing that popped up was a bunch of games made by Rare Ltd.

My time was short so I came home.  We'll likely go back there this weekend or next weekend and when we do, I want to buy some games for the sole purpose of selling them.  I lucked out a few years ago and bought a copy of Shadow Hearts 1, Disgea 1, and a couple of Pokemon games (the Poke' game were given to me by another guy).  I traded them in at Gamestop and wound up with enough store credit to totally pay for my DS Lite and a horizontal Wii stand.  I was shocked.  For the $20 I spent at a movie rental place that was going out of business, I wound up with maybe $200 worth of swag!

With your help, lightning may strike twice!  High trade-in value or resale value.  That's what I'm looking for!

Usually the game has to have a limited number of copies made like Stadium Events which was renamed World Class Track Meet (the game that comes with the power pad if you bought the deluxe NES package).

"Other rare console games include "Nintendo World Championships: Gold Edition," "Kizuna Encounter" and "Bangai-O: Prize Edition."

http://articles.nydailynews.com/2010-02-14/news/27056248_1_ebay-auction-bandai-nabs

That articles talks about Stadium Events being posted on ebay for 9.99 and ended up selling for 13,000+ due to being rare game and still have the box.  Almost any game can sell pretty good if it is still in the box (never opened).  I know the unopened Fire Emblem GBA games go for a lot.  Metroid Prime Trilogy for Wii is pretty damn expensive even used on Amazon.  So pretty much every video game I've bought I should have bought another copy and just left it unopened.

JRPG's tend to hold their value / increase in value over time, I've found.

Tbh, when doing something like this I just use amazon on my phone to check how much stuff is going for if I pass something I think might sell well. Obviously stuff like a yearly sports release isn't worth much but something that sounds or looks obscure would at least be worth a search.

Good luck!

How about typing "expensive vigeo games" into google ?

This was the first hit: http://www.racketboy.com/guide/the-rarest-and-most-valuable-video-games

Metal Gear Solid: Twin Snakes for the Gamecube and Xenogears for the PS1 are the only two I can think of right now.

Yeah keep an eye out for Twin snakes.
ICO would probably fetch a good price.
I think one of the Persona games on the PS2 was pretty expensive when I was looking.
Good condition PS1 Final Fantasy games (black label).
Most Nintendo-made games have great value long after release.
Also stock up on as many sports games as you can, those are priceless.

Here's a site for rare Atari games, I don't know about other consoles
http://www.atariage.com/

I've gone to flea markets a few times hoping to hit gold but it never happens. I wouldn't get my hopes up.

Well, I already have MGS Twin Snakes for the 'Cube. I don't wanna part with that. And when I did type in most expensive video games, I got a list of games so rare, I KNEW they wouldn't be hidden amongst the titles. I was hoping for something more along the lines of Chrono Trigger which I sold for like $85 back in 1999 or like the titles listed in the OP which combined netted me over $200.

Most games decrease in value. I was hoping to find a few that I could sell to Gamestop or online for $50-$100. That would make it worth my time.

I DO have a copy of Illbleed for the Sega Dreamcast. That game has aged horribly. I looked at amazon.com and I saw that it was selling for over $100.....but there were also copies of the game selling for $30. I think I'll just hang on to it.

Check gamegavel.com to see what folks are paying for certain games. Although to be blunt, most of what you'll find is going to be trash.

Oh and there is that one game on the dreamcast, Panzer Dragon.