Mustang II suspension works great on a Merc, and yes it is expensive with a quality suspension package running between $1800 and $2500. If your fabrication skills are above average you can install it yourself.

And yes, all shops want to sell you things and make money, that's how we pay the bills!!! I could say that most people who come into a shop think you should sell them parts at cost and install them for free, but I won't!!!! Tee Hee Hee