The old units will pop-up on eBay at a rate of one-two per month, and they tend to sell in the $200-500 range, depending on whether there are routers or bits included, the overall condition, and the copyrighting skills of the seller. I’m not kidding about this last point. I've seen pristine SS tools go for next to nothing because the seller didn't bother to talk about the tool. In other cases I've seen worn-out tools sell above the current retail because the seller was a wordsmith! (The Ron Popeil fan in me has to respect that on some level.)
The video below shows a Shopsmith Router Arm being used to make parts for a cheese fountain.