The cost is 160 Euros. There are already buyers for all of the first run. Contact Rob (Basvarken) by email or PM for more info.
Re the body shape: it's strictly a trademark issue, nothing to do with patent or copyright.
Gibson may not have registered a trademark on the Firebird/Thunderbird, but they would probably assert common law trademark rights if a copy was too close.
That's probably not really an issue with a Fenderbird type since a bolt-on Fender-style neck on a Gibson-style body is not likely to be confused with a Gibson product. But it might be a big issue with a clone, even if the clone isn't officially marketed in the US.