Relays or FETs aren't a big deal.
If you can deal with a single color LED, one of these guys could do you well when mixed with a relay and/or FET for solenoid tripping. They offer more advanced models as well of course, I'm just going for small.. Not that you're worried about small.
Part of the issue is I/O, you may see some lag between ball in breach and eye allowing the solenoid to fire.