For pricing, the SmartThings hub is $80, water valves are about $100-$200 each depending on which one you go with. Nice thing about SmartThings is that they have generic handlers for devices and you can connect any Z-Wave or Zigbee valve to the hub.
The hoses cost about $100 for my 2 yards. I went with some cheaper hoses. For the Sprinkler heads, they were about $40 total (Home Depot has a 2 pack of impact heads on spikes for $8).
Finally, an 8 Zone Rachio is $199.99.
So I’d say from scratch, for my lawns (which are both fairly large), it would cost around $700 for the Rachio, ST hub, valves, sprinkler heads and hoses. In comparison when I got an estimate to put in irrigation, it was around $3000+