Well, to the trained eye, watch for the size of the table, whether it has the center piece for the blade hole, look at the type of spring at the rear. Newer ones have a coil spring rather than the zig-zag type. It should have the tension lever at the front(rear ?) and a Quick clamp to make it all right. Then, ask for all the blade clamp holders, and the Tee wrench. A quick look at the bellows too. They are usually shot but can be replaced by a CV boot. Make sure it's a variable speed too. If it has all that stuff and looks like it's not been run over by a truck, it's a good deal at $500-600. Nothing more because they pop up all the time. I'm watching one now that has nothing mentioned and the seller thinkis it's worth $1000 because he looked them up on the net and knows nothing about all the changes over the years. I've contacted many sellers trying to educate them The one I bought for $40 I told the seller they were nuts and it was worth 10 times that amount to the right buyer. She said they just wanted it out of their garage so I drove about 75 miles each way to get it.