Buy it. The MP Prime mold is being retired by Takara, and Hasbro already stopped using it about 6 years ago or so. Unless it's DVD Prime, $60 is a bargain. Well, to me anyway. Just be sure he really is complete before you commit. EDIT: Wait, are you talking about buying or selling? Because if you're selling one, depending on the version, no that's not too much. You might be asking too little if it's the Original MP-01 by Takara, but if it's either Hasbro version, $60-$80 is about the right price range.
If you sell it on eBay, you'll get the most cash for it. If you're buying it, then $60 is basically a steal.