I know this is digressing from the topic a little bit but I figured I might share this information in case anyone's interested based on personal experience working with the product. As mentioned above, Novec 1230 is made by 3M for use as a fire protection extinguishing agent - namely, a halon alternative. It is one of many chemical compounds that have excellent environmental properties when compared with other clean agents (ie. halon alternatives). As for price, this is negotiated with thier OEM's but you could easily guesstimate anywhere between $12-20 per pound depending upon quantity. At 13 lbs/gallon, it won't be cheap for the common home or even power computer user.
With that said, there are a number of other chemical compounds that would be appropriate for this application that might be a bit more reasonable. I have some personal contacts that work on the Research & Development side at 3M on products used for refridgeration/cooling and would be willing to help anyone interested on a particular application and is something that my firm is starting research on. In fact, the Crayes supercomputer is operated in a 3M di-electric cooling fluid....
As for experience with pumps, we have just completed two years of research pumping Novec 1230 and I can attest that flows beyond 50 gpm are possible provided the right choices in piping and pump selection are performed to compensate for the slight vapor pressure. With a SG=1.6, it's a 'bit' heavier than water but with dielectric strength up near 60 KV, contact with electronics is not an issue. Similar 'engineering' is necessary for the other non-fire protection products but pumping shouldn't be a problem for smaller flows as long as you can prevent cavitation.
-David
http://www.capsfire.com