Running or not is almost irrelevent, it'll cost a few hundred quid at the most to sort even if it's seized. It probably hasn't run since it was on the road in Japan maybe 10 years ago so they probably just don't know wheather it runs or not. If the bodywork is o.e. and near mint it's value is whatever someone will pay for it, after all there were only 1000 ever made like it, some of that bodywork now will almost certainly be unobtainable and you could put up a very good case that it (a Rothmans MC21sp) was the best NSR of the lot ('21's "better" than '28's, SP's the one to have, Rothmans are the prettiest of all) and thus it is the NSR to own.

The value of '28's and 28sp's in particular has always been higher for some bizzare reason and recently has gone even higher still, wheather '21s sp or otherwise follow them is up to buyers, there are so few around the value can change very easily, if someone pays £4k+ for this then that's what a mint 21sp is worth today, what they were worth 2 years ago is of no concern.
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