sigh.... if I had the space in our backyard there'd be a Eureka out there getting built right now. I've loved these since I was a kid, and found one locally that would have been a great restoration job. Unfortunately, we needed a 'running' car and didn't have the luxury for a project. So we bought the Defender instead :D No complaints!
But still... I had a close look at a few. Some solid examples are going for $20-$30k, which is a lot for a fibreglass kit on a VW shell, but yes, they are becoming rare. Examples that are a bit rough do exist and would be great backyard projects. Some parts are hard to source (such as windscreens), but still a lot of fun. Some are appearing with rotary engines or even out of an Alfa. The hardest part it appears is getting the buggers registered if you don't have a good registration history on the car.
As for the Bolwell, yep, they are building a new Nagari. Saw it at a car show recently along with a lot of old examples. Turnkey only, with a V6 toyota engine. A bit funny looking from some angles, but very modern, very nice.
