There are a ton of variation in pricing on the ProCharger product and the Vortech product. On the upper end i think Vortech has pushed ProCharger to make their premium offer better. I think you are looking at roughly $10k for a complete set up capable of 30-35 lbs of boost. I know some of the dominant users of these products are getting the base compressor drive for a low fraction of that cost. There are a lot of very high speed moving parts in these things (think 30k rpm) they don't like being pedaled .... but they are still be developed and improved.
Looking online the Vortech V30 123A is $6200 (just the bare compressor, no gear drive, piping etc.) and the ProCharger F3R-121 is comparable for the base unit.
Not too long ago most guys I knew racing them carried more than one. I'm not sure i know of many folks running a 14-71 making 3000hp or less carrying a backup huffer .... but this is a bit out of my league. when one of these spits its guts up it sends some pretty nasty stuff through the motor ..... that is not the case with most traditional superchargers. But traditional superchargers are big and heavy, like they were designed for a truck .... oh wait, they were.....
There are a number of people running complete motors for 10 races and selling a working set up turnkey. Some people feel comfortable buying their horsepower that way. Like a turbo, they can be idled around the pits with no issue. So a lot of people that run alone find that appealing.
The combination has helped the car count. I don't know if its cost, or more likely the fact that the carburetor is self tuning in most situations whereas jet changes in a traditional blower set up are mandatory ... and you see a few people out there rather regularly trashing complete traditional blower set ups (too lean or way too rich, both ends can kill you) vs what you typically see in the pro charger world is burnt pushrods and an occasionally trashed compressor unit. Exhaust pushrods in all high output engines open against a TON of pressure .... its not an easy job.
Some of the blow through carb set ups you see on these are beautiful .... and a Proline motor with a pro charger looks like a piece of art to my eye (roughly $85k with no tune up)