After the ZX-R there was the ZX-R mark2 and the ZX-RR, both updates of the original ZX-R, before the ZX-S and ZX-S Evo.
The ZX-S was never imported to the UK by Ripmax, maybe due to the price but by 1996 Ripmax wasn't supporting buggy racing anyway. Tower Hobbies did sell them in the US, but based on their prices its retail price in the UK would have been around £400-500 - in 1996
. Couldn't see them shifting many at that price when competition buggies were around £200.
The later ZX-S Evolution was only available direct from Kyosho to special order, which made it a Japan only release, unless you wanted to get every spare to order from Tokyo.