2002 Volkswagen Jetta Problem and repair cost

My engine started to make a loud ticking, kind of like when you put a playing card in the spokes of your bicycle as a kid. I was on the highway, after about 15 miles, I was losing power, made it to an exit and after a puff of white smoke came out of the tailpipe, engine quit. Engine wanted to re-start but with loud ticking. No fluids leaking from underside, except clear water drip.

Road service talked me into using their shop instead of one recommended by Enterpirse. Having no experience with either shop and mistrusting all repair shops, I OK'd just taking to the tow repair shop. They have just called for autorization to remove the valve cover.

Fearing a valve job, I thought I'd be proactive and get a ball park on what that will cost. If they seem fair, I will use them. The car is in Portage, Indiana.

Thank you!