Installing the monitor in the headrest - Toyota Avensis, 2.0L, 2004

Soon I will go to Novosib with my friends. I want to buy a headrest with DVD and monitor for my son. Found a cool one. Everything is stupidly built into the headrest. Technically made. But ... Expensive. Such a thing costs 18 rubles. It's a pity for money. I'm looking for other options for implementation. And then go 12 hours. The son will be bored. I want to do at least some kind of entertainment for him.