Your "sling blade" is actually a sythe and is quite common but not many people use them anymore. In my area of the Midwest they go from $5-$25. Your 2-man saw is also fairly common and not use much except for decoration...probab ly $25-$40. Early 1900s on both. I have a sythe and have had one for years that I use on 4'-6' tall weeds. I do not use it much because it is a lot of work.