I don't if this will sound silly xD
But a very good way of saving money and eating well is eating in university canteens! at least here in Portugal...
If you actually are a college student it's great - your student card will give you access to eating there.
But even if you aren't, in most canteens they don't ask for cards and many people (foreign/ highschool students/ others) eat there regularly, and it's okay.
A meal with soup, main course, dessert or fruit and bottled water costs 2€! And, at least here in Coimbra, the food is good. We have like 4 canteens, and one of them has a vegetarian option.
If you come from September to middle of July (I suppose the only month that the canteen closes is August... and maybe the 2nd half of July) and plan to visit cities here in Portugal this is a good option for you to save money and have a nourishing meal
and a PLUS: you get to know lots of people!!