largest telescope on a EQ3-2 mount?

For now i have a EQ3-2 mount with both axis driven and a 90mm refractor. I'm
just a poor student so i don't have a lot of money and i'm wondering what
telescope would fit on my mount so i won't have to buy a new mount? I
doesn't have to be a refractor because they are expensive. Is it really less
expensive to buy a telescope without mount and eyepieces or not? What would
you recommend?
Let me tell you again that i don't have a big budget like some others....
Let's say about 600$.