I am of the opinion that this backhoe is unique. And that the price should be unique as well. Your project combined both function and art, and there is an active market in both. The drawings themselves could add a lot of value to the entire package, as would a portfolio depicting your elaborate design process. I'm sure there is much more that you just didn't have the time or space to share here with the TBNers.
The existance of these many pages in following the project here at TBN is proof enough of the project's popularity.
Just like some of the others have suggested, I would also price the backhoe itself at the same as a similar commercial model, but that's not how I'd go about selling it. It is simply too unusual and too beautiful for a simple implement sale to accurately reflect the value here. The whole adventure becomes a package, like a song or a painting.
Consider this: If the sale would includes your beautiful hand-drawn plans.... plus links to various blogs discussing the project....and perhaps including a a promise that obligates you to give occasional talks on this type of combined artistic engineering & design/construction....that type of package might spur interest from an entirely different market. If so, it would raise the overall value considerably.
I happen to think that those additional pieces turn this backhoe from a tool into a tour of industrial art. Sold as such, the total package could then be worth considerably more than a simple implement. Naturally that would include the drawings either framed or bound into a volume as well as some of your own participation - and would probably be marketed through an industrial arts agency or gallery. That would put the emphasis would be on the art and the design rather than just on the ability to move dirt.
In my opinion, you've done an amazing thing.
Congratulations and best of luck,
rScotty
