That very much depends on your location. High tourism locations will often have lots of junk food places. If you can move larger distances (i.e. rent a car and the like) you'll find wonderful and cheap restaurants pretty much anywhere. Even in otherwise expensive places like SF or NY.
Here's the problem though: portion sizes are _enormous_ . It took quite a bit of time to adapt, and adapt I did, if my measurements are any indication. If you want healthy portions, you'll either waste food, or you'll have to ask for a take out box. Essentially, a lot of places will serve you portions that are enough for two meals.
Ingredient availability varies a lot. In larger centers you can find almost anything you could possibility want. Even farmer's markets if you are lucky, which will often have locally sourced produce at lower prices compared to big supermarket chains (and sometimes even lower if you get there near closing hour ;) )