Most larger hardware stores, in their watering/garden section, sell watering timers such as Orbit, Pope, Rainwise, Toro etc. Most also sell the 24 VAC valves which are generally setup to connect to 19mm poly pipe.
Most dripper type applications use a 19mm main feed line & then run the smaller 4mm dripper lines teed off the 19 mm mainline. The valves, poly line, drippers, connectors etc are generally all sold in the same watering/garden/irrigation section