Recaros are proper.
Their genuine bases cost about £150 each, so £150 for a pair ain't bad. With a Recaro and a standard G2 seat side by side it should be possible to figure how easy it'll be to set up a homemade base. I don't think it'll be that easy as Golf2 have three mounts, so you're going to need to be reasonably cute with the fab and you'll need a base to butcher for the fabrication.