Arborwiki has a great page for where to get cheap lunch in Ann Arbor/Ypsi.

I can attest to several of these:

Kosmo in Kerrytown is the whip. The Korean stuff is more than 5 bucks (but such a worthy splurge), but the Kosmo burger is really good and cheap, cheap, cheap. Also, a great place to eat with kids, since the grilled cheese and hot dog are actually priced to reflect the (gasp!) real cost of a grilled cheese or a hot dog. While you’re there, say hi to tennis aficianado and owner Don Kwon, as well as counter mistress, comic artist, punk rocker and super zinester Tavi.

Also try Eastern Accents, on 4th, for these yummy buns with meat inside… they’re around a buck-fifty, and there’s something pretty authentic feeling about eating a bun with meat inside it. Although I guess it isn’t that different from a corndog, really. I just shattered my own illusion.

Pita Pita on Washtenaw is my favorite middle eastern in the area (although Star’s Cafe in Westgate is a by-a-nose second), and gets full respect from my friend and colleague Khalil Hachem, who is bona fide Lebanese.

The $1.55 tacos at Sabor Latino are so good in the summer. If you’re looking for Taco Bell- style, this isn’t it, but if you love really fresh cilantro and corn tortillas, they’re perfect. I think it’s my favorite cheap summer lunch.

The fact that the soup at LeDog is really good is EVERYONE’s best-kept secret, so it’s not really a secret anymore, now, is it?