You don't really need an expensive site. You can get a good one for about $30.
Gotta disagree here. Dont skimp on a sight. Especially if your going to be spotting and stalking and hunting from the ground for elk. Get an all metal sight, and it will hold up much better. You dont want to discover your pins are broken and the sight housing is all bent out of shape when ur drawing back on your first elk with a bow!