Mazda was adept at selling limited editions, In 1994, there would be a 1 in 3 chance that a new Eunos Roadster would have been a R-Limited, RS-Limited or G-Limited.
There was some debate on Miataforum about the wood used in later Nardis fitted to NBs. One strong suggestion was that it was Birch, stained.
But that is academic.
The issue is that there appear to be amateurs setting themselves up advertising steering wheel restoration, when its not really a restoration. Stripping the varnish off the wood isn’t restoration. The approach to truely restoring a steering wheel would be something like Nardi’s approach to restoration; splitting the wood along its glued join to allow the wood to be reworked, inspected and replaced if necessary.
Objectively, regarding the £270 price is fair. Given a garage rate of £100 an hour, its probably fair enough. There is easily 2-3 hours work.
But a wheel like this takes longer, and needs a knowledge of how these wheels were made:
https://fahrenautos.co.uk/steering-wheel-repair/
Ferrari Californias, er, spent most of their time sitting in a predominantly Californian sun (most ended up in the US).
Fake Nardi, probably uses Monkeywood
Even faked the little blue cloth bag. 
