Yep, I checked with Jon at GZG a few months back. He no longer has the facility to produce resin vehicles and the molds for that particular model weren't sold with the rest of their 28mm SciFi range.
He was open to the idea of bringing that particular tank model back into production somehow, given enough demand. So it's well worth dropping him a line expressing an interest. The metal Eureka version is WAY overpriced IMO. Seventeen quid will get you a Heavy Landship from Ironclad, Black Pyramid or even Scheltrum.
Dr V