We have a $600 or so cot (Sunbury), and I love it. It has those plastic clips for the sides, which are just so easy to use, and it dismantles in about 2 mins which is great when you have to move it room to room.
Its a big chunky one, with engraving on it, and while it seemed expensive, I'm happy because it gives my nursery such a nice feel.
I'd buy what feels right, but juts make sure it has 2 mattress positions, and 2 side positions, and easy to click in sides, and you should be right.
Fi