Well, if you have an Android phone/device, the best app to help out with this is CCG Fair Trader. There are a lot of apps that let you look up one card at a time, or even a few at a time. CCG Fair Trader, however, lets you create multiple lists of cards and compare any two of them side-by-side. You don't have to remember or write down the value of each card you look up. You can check the price of a bunch of them all at once!
The prices are live and continuously updated by tcgplayer.com. The guys at tcgplayer.com get card values from many vendors online so you know you are seeing the fairest price available.
Here are a couple of screenshots to give you a better feel of how it works/looks:
In case you didn't notice, there are actually some cards from other games in that trade. CCG Fair Trader can store card lists with cards from five different games: Magic the Gathering, World of Warcraft TCG (WoW TCG), Pokemon, Yu-Gi-Oh!, and Redakai.
If you play any of those games and ever make any trades, this app will make that a much better experience. The full version is costs a little, but there is a trial/lite version for free that limits your card lists so you can get a feel for how it works. If you ever made a bad trade since you didn't have the right value information, you know that the cost of this app (currently $1.49) can be pretty small in comparison.
Check it out on the Android Market. If you have any questions, go to the developer's website forum or send an email (info at littlepancake dot com).
