Velodrome found a nice set of chains in another thread, needs to be here too
They're from a company called Slipnot - bicycle traction systems
. Those prices are for each tire, so compare that price to a single "pro" studded tire...
Found a review of them, w/vid over here
I like the idea of being able to pop them on/off in 5min, might have to check out a pair this winter.