Be sure to check depth of the wear indicator groove on braking surface to make sure the rim isn't worn out or nearly so. Also look for any other obvious indications of damage or excessive wear.
Why buy used, when you can get this deal at CompetitiveCyclist.com?
2009 Cycleops Power Tap Comp/DT RR 1.1 Complete Wheel - $659.99
I've got a bazillion wheels laced with MAVIC rims because they are just easier to source, BUT that is also why I have frequently recommended that people try to locate some AMBROSIO rims (at least one model is available under the "Colnago" label, so if you have a Colnago dealer near you, you can consider/buy/try the Colnago rims) ...