Restaurants in Placencia are pretty much affordable. It all varies on what and where you want to eat. There are several Creole restaurants right in town such as Omar’s Creole Grub, The Galley, Dawn’s Grill N Go, D Thatch, Wendy’s Creole restaurant, where you can get breakfast, lunch for US $5 each.
If you want a less casual dining/night out you might want to check out Maya Bistro and Mojo Lounge. These are more American-style restaurants and will cost you US $20 and up.
I can’t forget to mention, if you want Chinese food there are several restaurants right in town where you can get a meal for US $5 and up.