Protein filled snacks

It's easy to find a load of recipes online to make your own cheap protein bars, that are just as good as store bought (and you know EXACTLY what is going into them)

lowfat cottage cheese
Fage Total 0% all natural nonfat greek strained yogurt (18g protein but it's not too filling if that's what you're going for)

Low fat or fat free greek yogurt (Fage is the best brand, in my opinions). I love to pair it with fruit and a bit of stevia.
1/2 cup yogurt + 1/2 cup (80g) sliced strawberries= 90 calories, 12g protein, 0g fat, and 100% of your daily intake of yummmmm

Veggie omelet/scramble. The veggies add some good bulk and nutrients, and the eggs are a good source of protein. You can use whole eggs if you want, but I like to use egg substitute because you get all the protein with half the calories.
1/2 cup egg substitute (the equivalent of two whole eggs) is 60 calories, and contains 12 grams of protein and no fat. 2 whole eggs are 140 calories, have 12 g protein, and 5g fat. Pair either with however many vegetables you want, and you've got a healthy satisfying snack.

Beef jerky. Make your own, if you're so inclined. Watch the salt, though.

Hard boiled egg whites are my go to. For something a little more "on the go" I like Quest protein bars.