Katilsu, here's my thoughts on budget-friendly dining.
Lunch is always less than dinner. Aim for a mid-afternoon PS--2:30-3:00. But check ahead--some places may close from 2-5. That way you can arrange your eating to be ravenous for your PS.
Buffets are $$ but you will leave hurtin'. For characters, Chef Mickey's is the gold standard. If you could only do one character meal, this is it.
Be aware that Liberty Tree only has characters at dinner. The food is the same, but you eat alone at lunch. (personally, the food at Liberty Tree doesn't do much for me. It is "Presented by Stouffer's" and is the same turkey and dressing available in your grocer's freezer. There is nothing wrong with it, but it is not really special)
'Ohana is a wonderful choice, but no characters. But be careful, at $8 each, those fancy drinks add to the bill quickly.
Another option is breakfast. I realize that college students tend not to be morning people, but there are 2 ways to approach it.
1) Early PS -- 8:00 at MK. You should be finished eating, or close to it, befoer rope drop. It is a rush to have Main Street to yourself.
2) Later PS -- 10:00 or so (you could do Hollywood & Vine at the Studios for this one--they don't open before park opening like Crystal Palace does). With any luck, you can last until dinner time.
Breakfast tends to run a little less than dinner (but I don't know why, since I personally can eat $15 worth of bacon!).
Generally speaking, even at the sit downs, portions are huge. People with a normal appetite could easily get by with an appetizer and 1/2 of an entree.
Check menus on line--they are really useful in helping you decide.
Many people suggest going to 50's Prime Time and Sci-Fi for milkshakes or dessert. I think this is good advice. Their food is not worth the $$, IMHO.
The belly dancer at Marrakesh is a good time....