I would imagine that some form of "Cuff" has been about since the first idiot decided that walking on stilts was a good idea even if it was just a length of rope to tie your leg in place
So patenting them as just a cuff would run into loads of problems but as an attachment to Bocks they could have a patent but it would be easy to get round if they could fit something else
A bit like snowboard bindings try patenting them now and you will find it hard unless they are radicaly different to all other bindings
The cost is normaly due to them being made in low numbers, if you have one made it costs a fortune, a short production run a lot less and full blown mass production cuts the costs by massive amounts
Sadly we are in the small production bit heading to the mass production league if they start to be fitted as standard
So they are gonna be expensive just like the first Bocks started at £600+ and are now down to £135
so the more of us that buy them the cheeper they will become
Jason