I also was once in kollel and our shabbes was not even close to 70 dollars if we wanted to save
1) fish, one roll can last for 3 weeks for a couple
2) soup is cheap to make
3) meat- why do you think meat is a must. Whats wrong with chicken?
4) my wife made her own coleslaw and kugel
5) my wife made her own challe
6) tshulent isn't so expensive for 2 people if you don't put 2 pounds of meat in ii
7) liver and egg was homemade
schnitzel and kugel for after tshulent as well and one pack of cold cuts is more then enough
I would say half of 70 dollars can get a couple a decent shabbes.
Problem is today one expects London broil and a lot of stuff get bought and not homemade....
If you want to save you can, it's just a question of effort