Pattaya is an awesome place especially for poor retirees. For 10,000 baht you have rent in a beachfront condo with gym and pool, elec and water covered. Food is fairly cheap if you cook at home. Lots of ways to spend your day that aren't to expensive. Movie theater is like 240thb, bring your own snacks. A small cooler with beer for the beach with your friends.
I'm not putting a $$ figure on what's needed, but what a great place to end up if you only have your pension to live on.