I was reading a review on them this morning i can't find the link again, but the review said for the price they're great. I know now they're $169, another alternative that is about $50 less than a Velocity set is the IRO wheels $199 for all silver and $219 for all black. Those i'd look at as well. I'd say you could also look at Weinmann DP-18 for $175ish shipped on ebay, some say they break, some say they work, i'd say its up to you. But those are what i'd look at. I just bought a bike with Velocities and have dreamed of owning them so i'd say go for the Velocities but thats me, the IRO and Alien seem like great deals for the price if you dont want to drop $275ish on some Velocities IMO.
Edit: Just found the review/article. It was on fixedgeargallery.com here it is
http://www.fixedgeargallery.com/reviews/alien/wheelset/