I'm currently offering 1100 CE for each TF2 key.

I'm planning to buy several dozen, so if you're selling in bulk (10+), I'm willing to negotiate price (within reason!)

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The best deal on energy from the Energy Depot is $1 = 450 CE, and that's when you buy it $100 at a time.

TF2 Keys on the Steam Market are currently going for about $2, so they're worth about 900 CE straight across. For the latest prices, go here:
http://steamcommunity.com/market/

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I'm busy during the day, so if you're interested, please send a friend request, and we can use the new friend offline trade for convenience. Here's my Steam profile:
http://steamcommunity.com/id/mrducks

Thanks!
Mr. Ducks