you pays ya money... Resale value is a tough one. In theory they hold their value but in practice so few people buy one it's hard to know for sure. Don't buy it for the resale value, buy it for the noise and the fact you'll rarely see another.
I'm having mine px valued tomorrow with my SC for an evora 400, and I reckon the dealer will offer 14k. Don't worry, I'm not selling as the only 400 id want is a roadster which they don't even make yet! Just passing the lotus dealer so have asked for some figures. (2008, 70k miles, 5 owners, flsh, okay condition). In fact just had 8 yeah MINOR service at Sidcup which cost 600! Inc mot and air con gas. ouch.