As far as wifi enabled printers go, I've had far-and-away more luck with Cannon than any other brand. I've never had any issues with built-in Google Cloud Print either. You can often get their lower-end three-color+black models for less than $40 or sometimes free after rebate... as you move up the line, you add more colors like photo black, grey, etc but it sounds like this wouldn't be of any benefit to your parents. I've also had better luck with inexpensive third-party ink on Canon printers than any other brand, which makes them particularly economical. Something like the MG2920 should do everything they need.