Most of the items for your boxes can be handmade or found at secondhand stores making it a nice budget item. They can be as complex or as simple as you like. I would suggest laminating papers like maps or brochures when possible though (by machine or self-laminating works).
Choose specific things related to that area like food, pictures of landmarks and people, maps, clothes, toys, and dress up clothes.
Here's a picture of my box of Qatar and Sri Lanka. Now, this is a bit different because I visited those places and was able to collect a variety of items but similar ideas can be used for other places around the world. Pictured is air sick bags, a photo album, sea shells, an Arabian Friends doll, elephant puzzle, a man's blue hat, a girl's sari, a maraca, and a book.
Because this was made when I was working at the daycare I have everything listed on the top of the box as well as suggested items to add during play (like a camera, jeeps, and turtles.)
Make Up/Hair Salon/Spa
At the daycare I worked at we made this into a day activity. They had to build their shops, make store signs, figure out prices, share jobs, and of course do some spa work.
We used real items but for extended play and younger kids that may not be the way you want to go. See some examples here: spa, hair stylist, make up.
Will you set up a travel agency, airport, or airplane?
There's so many ways to make play food, here's just a few ideas in a previous post and here's a cafe!
Store options are endless. Grocery store, florist, and bakery are a few ideas I've seen floating around.
Help people or pets feel better. Don't forget your x-rays!
Everyone loves smores over a camp fire.
Make fossils, match fossils to their imprints, dig for items too.
So many things to learn!
Fix them up and then wash them too!
See a film or make your own movie with toys and puppets.
I've made a previous post about how I made a garden, see it here. Does the garden supply the florist or the farm the store?