Armalites (m4s) are TM's weakest models. If you were interested in an AK, or an m14, people would suggest TM. However, since it's an m4 you're after, I'd steer clear of TMs. Besides, that gun you listed is $465, only $35 away from the "steep" price tag of a full metal gun.
You'll be able to find a better gun for that amount of money in the classifieds. PM a local age verifier to set up a meeting