What do you think? Help

[Mondeo]

Hi all, well i have had some trouble with my first car a 1996 Mondeo. Was driving when all of a sudden the engine stopped. Trying to turn it over i could hear a clunking sound inside the engine. Towie towed to a mechanic that was recommended by friend.

Now the mechanic tells me that all 12 valves are broken and will cost me $600 for every 3 valves. I have no idea about engines and was wondering if anyone thinks im being ripped of? Do 3 valves really cost $600?

If anyone can help or offer some advice it will be greatly appreciated.

Thanks
Mondeo