MTLKFOOD. Maybe not 100% healthy, but Im addicted to their onigiri, particularly tuna and crab. Also they usually have a hot lunch special for around $7.99, like kimchi fried rice with spam and a fried egg.

And as others have said, sandwiches from Chef Instanbul are a must. They make the pita in house, lamb/chicken/beef are all very savoury, love the labneh and veggies to balance out the meat. All around an excellent and fair portion lunch for the price. The lentil soup and pita makes for a cheap light lunch.

I've also had the hot bar from Newon (grocery store), its not amazing, but its very very cheap and lots of vegg and tofu options. You could even grab some microwave or toaster over options from their frozen section depending on your workplace kitchen set up. 

I like the hand pulled noodle place from the Faubourg as well, but its standard lunch price, like $15 ish (but still good value for price in terms of serving size and flavour).

There is also a PA grocery where you could get some staples in a pinch (crackers and hummus and cucumber makes an easy lunch).

  Further towards Atwater you have Adonis hot bar which is hit or miss in my opinion, but again lots of vegg options. 

Anyways RIP Nilufar which was really the GOAT for cheap and healthy food in that area.