Not sure what DYE would charge but if you can read the SMC part number it's probably going to be £40 to £50 from a pneumatics supplier. Doubtfull they would stock one though as most pneumatics suppliers only stock 24V (industrial) solenoids.
Is it definatly broke?
Try pressing the orange button with a screwdriver to see if you can fire it manually.
OK but there can be a number of reasons why it would appear that the solenoid is broken. It could be a bad solenoid harness (loose or broken wires ). A broken board, etc etc etc.
If you bought the marker you could send it in to be checked out and that way you wouldn't be spending money you didn't need to.
The solenoids in question have a very low failure rate.