Where's the cost? A couple of merlins and some plywood....
I understand the fusilage parts were built in woodworking shops up and down the country and transported for assembly. All pretty low tech.
I reckon the real cost is actually in the tooling and jigs. Once the first one is ready the next will be easy. Then there's the paperwork of course.
At least there won't be the complication of four olympus engines to maintain.
Oh you have no idea what "from plans" means. To do it right, there's going to be a crapton of fabrication of fittings and fiddly bits of metal. Heck, sourcing the right mild steel for that stuff can be a real PITA. They may end up winding their own wires.
The replica folks I talk to that build from original plans are absolute nutters in getting it exact, and it takes a huge amount of man hours to build one.
The only problem is that when they are done it will be better than factory built.