It depends on where and which you get. I know one person just had blue tegu hatchlings for sale for $300 each. My hybrid babies went for about $175 I believe(I did not sell them directly). I've seen Arg. B&W babies for sale for around $100 each. Reds can run around $200. All prices are from my somewhat faulty memory.
You do want to be CERTAIN you are getting a Captive bred one. And be certain you do not get a Columbian, or a gold tegu. Those are much more likely to not tame down(although I know folks who say they have one that is tame, all the rest I've seen or heard of were wild little buggers that loved to bite).