The basic guts to a fast charger are built around a monster DC power supply. The control logic about how to turn it on and off safely (only once the plug is properly seated in the car and the car is ready) and adjust the charging rate is the bigger issue. The plug hardware is defined, so that brings us back to the control logic. To give you a rough idea of a controller cost, www.emotorwerks.com has a chademo controller they sell for about $600 that works with their DC fast charger. I'd expect eventually, they'll have a CCS controller, and it will likely be similarly priced. Note, this is not a stand-alone product, it becomes part of the fast charger and isn't likely to be something that could easily become an adapter cable.
Can't speak to their durability or performance, never seen or used one, but their level 2 units seem to get good reviews (not particularly pretty, but they work). Throw in modifications to basic DC fast charger and labor, and you're probably talking about $3-4K by the time you add in a cable and plug - something that may be a bit much for some to want to subsidize. That's if their design would allow that modification easily, otherwise, it could be a lot more effort to modify. The entire BMW 25Kw CCS unit has something like a $10K price tag, so my unsubstantiated estimate of about 1/3'rd the cost to retrofit some other unit to be compatible with the CCS standard seems reasonable, at least to me.
