I thought it was a great idea! Nope, I didn't investigate how much it cost. Google to your hearts content on that one. I did read that the deader the lawn the longer the painting lasts. You know like a woman that colors her gray hair? It grows and has to be touched back up. So if the lawn is completely dead there likely won't be the re-growth of roots to require touch-ups.
I received a call from my water company recently that said they were going to be giving us just a few days a week to be allowed to water our lawns. They already have that in areas of Los Angeles city, Glendale, etc. We have so many HOA's out here I wonder how they're going to handle seeing brown lawns everywhere.
At any rate, if you are a water conscious homeowner, consider Googling the lawn painters in your community and maybe it'll be a great option for you!