I was looking at using a magnetic reed sensor on the solenoid valve to trigger a timer on a Raspberry Zero and came across this thread and then also found the $90 version Prima is selling. I'd really rather not spend $90. How is this project coming? Has anyone come across a simple timer like that Prima one that I could source? I've already got the reed sensor to try out.

I've got a couple Pi's but would be first time wiring up and writing a quick stopwatch program. This thread looks neat, but got lost in all the side conversations.