It is perfectly usual for my nearly-17yo son to eat, as well as meals, every day, 8-12 weetabix/half a box of cereal, 2-4 packets of noodles, 2-6 packets of crisps, several bananas, and whatever he can find in the way of bread, beans, pizza, ready meals, biscuits, cheddar cheese, ham, bacon, eggs, left-overs...
For snacks I buy: cheap packets of noodles (11p from Morrisons or Sainsburys); cheap 12" pizza (59-79p); cheap cereal (whatever is on offer at £1.50/box or less); wholemeal bread because I find it fills 'em up better and they only go through a loaf every other day rather than every few hours; any fruit that is discounted; tins of unbranded beans... I don't currently buy ready meals, because they're expensive and I got fed up with cooking an evening meal, then having my eldest make 2 microwave meals between 10pm and whatever unearthly hour he went to bed... Apparently I am a 'cheapskate'. 
Interestingly, my 12 year old has adjusted his 'taste' in food, so that he has become vegetarian and now likes food my eldest won't touch: salads, olives, rice cakes, oatcakes, fancy cheeses like brie, all kinds of fruit... I assume this is a kind of curious 'self-defence' which increases his chances of ever being able to find a snack left for him to eat!