I don't know why they so pricey, except that they have to be built strong to take all the abuse. I have a Dynapac that I bought from a contractor going out of business. This was ten years ago and use it a lot. I paid seven hundred for it then and it was probably a couple of years old when I bought it. It has a Robin engine which I think is made by Suburu. The plate is steel and the vibrating mechanism (I don't know what it's called.)is very heavy duty and by it's self probably half the weight of the tool.The engine has always run great. I've replaced a couple of drive belts,oil and plugs but the main components have been reliable. If there is a problem,it's usually caused by something shaking loose. Before I bought this one, I would borrow a friends and it had a aluminum plate, it was much lighter but had stripped bolts in the aluminum casting that he was having a hard time repairing. I'm not sure how the lighter plate affects the compaction rate if it does but I did not want the repair hassles that aluminum has versus steel. This model I have was around $2800 new in the late nineties. Scott