Hello Darren,
yes, even Lotus has mentioned different numbers and I guess, it is also a mix of original Rivieras and retrofits. But definitely there are more than 3LHD.
The other car is chassi #1116 and is viewable in the fb register.
Yes, I think the price is a bit high in comparison with others and their condition. But generally you will get a limited number car with perfect handling, F1--heritage, sexy look, Targa and the very last car with Chapman influence on the engineering. There are some things which you get used to but there is no doubt that they are the better choice over Capris and their likes which will fetch much more money. So, they are pretty much undervalued and what ever you will pay, at the end it will be bargain.
All wedges are on the up and I would guess the called 4000€ seem reasonable.