They won't come much cheaper than that I'm afraid.
The Shakespeare version is cheaper, and just as rare, but the Spartons are highly sought after and reckoned to be the one to have.
Many on here will argue about the merits of a low rider tube versus modern high riders but that is a Marmite arguement. I love my Shakey but if a Sparton had come along at the right price I would have had one of them instead.
Now stop reading this crap and go and buy it!