I am still not convinced that a workstand is really necessary- all you need is a saddle tube bolted upside down to something. You can then put the bike upside down and slide the saddle tube into the bike frame (with the saddle and tube removed) to work on it. Apart from being really cheap the seat tube is designed to withstand some stress and their is less chance of damaging the bike than if you for example use a Park PCS-1 to clamp on the top tube.