If you want the biggest mashup of characters in your fighting games, Marvel vs Capcom 2 is the place to be.  It may not be the most balanced game for tournaments, but its one of the hottest mainstream 2D fighters out there.  Most gamers may flock to the PS2 version, but the Xbox  release is just right behind it in terms of value.  You can imagine how many fans would love to see this come to XBLA if they could work out the licensing issues.
Check for Marvel vs Capcom 2 on Amazon
Check for Marvel vs Capcom 2 on eBay

It’s a bit unfair to include Steel Battalion so high on the list as most of the value of the full set is due to the massive controller that remains as a mech fan’s dream come true.  However, even the bare game still holds its own in the top 10, so we can’t complain too much.  If you aren’t familiar with it, Steel Battalion’s controller tries to replicate being inside a Mech and had nearly 40 buttons. Because the controller was so large the game retailed for $200 and only limited quantities were produced. The initial production was close to 2,000 units but the game was re-released, adding a few more copies to the market.

Check for Steel Battalion on Amazon
Check for Steel Battalion on eBay

It’s not too often that a greatest hits re-release is more valuable that orignial releases, but in this case, it contains two excellent Sega titles in one.  The game originally sold for $19.99 when released (like all Platinum Hits titles) but now the game sells for nearly $40. The game released in December 2005 and like other late generation titles it wasn’t carried by many retailers.
Check for Sonic Mega Collection/Super Monkey Ball Deluxe on Amazon
Check for Sonic Mega Collection/Super Monkey Ball Deluxe on eBay

Halo Triple Pack is a bundle that came out rather late in the Xbox’s life resulting in rather small retail support. The Halo bundle includes Halo 1, Halo 2, and the Halo 2 Map expansion. Xbox 360 owners keep the price high because all three discs included in the package are backward compatible.
Check for Halo Triple Pack on Amazon
Check for Halo Triple Pack on eBay

Jurassic Park Operation Genesis is one of the more uncommon original Xbox games. You have to recreate the Jurassic Park theme park by creating dinosaurs, building rides, and attracting guests. Just like the movie, the dinosaurs can attack the guests if you don’t keep them safe. The game received mediocre reviews but it’s rarity makes it expensive.
Check for Jurassic Park Operation Genesis on Amazon
Check for Jurassic Park Operation Genesis on eBay

This is really one of the best fighting compilations out there, as it contains Hyper Street Fighter II and Street Fighter III: Third Strike on one disc. The compilations was already quite popular, but the buzz from Street Fighter IV recently helped increase the price for this game.
Check for Street Fighter Anniversary Collection on Amazon
Check for Street Fighter Anniversary Collection on eBay

Sniper Elite was released on the PS2 at the same time and neither version sold very well, but the Xbox version is the rarer of the two. The game is entirely based upon stealth and using long range weapons. The sniping in this gem is more realistic than most FPS games because it takes into account wind, your breathing, and even gravity’s effect on the bullet.
Check for Sniper Elite on Amazon
Check for Sniper Elite on eBay

Jedi Knight Academy sold quite well and there are quite a few copies available, but the game is very popular with Star Wars fans and received very good review scores. You play as a student at the Jedi Academy and complete missions assigned to you by Luke Skywalker and other Jedi. The game also has a network multi-player mode so you can compete with other Jedi in training.
Check for Star Wars Jedi Knight Academy on Amazon
Check for Star Wars Jedi Knight Academy on eBay

Grand Theft Auto Trilogy includes GTA III, Vice City, and San Andreas in one package. The game wasn’t released until November 2005, the same month the Xbox 360 launched. Most retailers quickly dropped support for Xbox titles after the 360 launched so the game was never fully supported. The game is backward compatible with the 360 and even with its high price is a relatively cheap way to play three GTA games.
Check for Grand Theft Auto Trilogy on Amazon
Check for Grand Theft Auto Trilogy on eBay

Fatal Frame is a survival horror game where your only weapon is a camera. When you snap pictures of the ghosts you can away their soul and protect yourself. The game was ported to the Xbox from the Playstation 2 but did not sell as well on the Xbox.
Check for Fatal Frame on Amazon
Check for Fatal Frame on eBay