I assume you have already taken a look at my guide to pressurized CO2.
Personally, the C would be fine. It has a working pressure from 4-80 PSI, and I think the low pressure gauge would most likely read from 0 to 150 (perhaps 200) PSI, meaning the gradations are still fine enough to allow for good control.
Dual stage regulators are nice, and offer some advantages over a single stage regulator. What you decide to get is up to you.
You may have more luck purchasing used Victor (or other industrial brand) regulators on eBay, and then removing the CGA320 nut and nipple and replacing with the European Standard. This will definitely cost less than the $270 it costs for a brand new regulator.
I am not sure what you mean by "other commercial brand" as Victor is just a particular brand (there are many others).
As for the solenoid valve, you can purchase these separately as well. Just make sure that the fittings that it uses matches the European Standard (BSPP, most likely).