I think it's this one, 2007, the decals are just really low contrast in the shady photo
2007 Cannondale T800 - BikePedia
$500 might be high for a MSRP $1300 bike that's 9yo. Consider what it might have cost on sale at end of season... Not sure if you have reached the bottom of depreciation yet like most of our C&V bikes. Bicycle Blue Book suggests less than $300
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Genesis 49:16-17
"Well, well!" said Holmes, impatiently. "A good cyclist does not need a high road. The moor is intersected with paths and the moon is at the full."