Do you know of a site or organisation that can offer reasonably accurate price guides for 'classic' or rarer type (potential classic) cars? I have the opportunity to acquire a genuine, unmodified LHD 1991 BMW M3 cabrio which has been owned by one family from new (two drivers), well maintained and used daily. Mileage is at about 150,000km and it seems pretty nice, but needs a bit of cosmetic tidying up. I cannot get an idea how much the car should be valued at in a commercial market (and by definition how much I might offer), having received mixed messages of anything from £6000 - £15,000. I know the answer to this question is probably "However much are you prepared to spend to get it" but I am sure there must be some way of valuing it. Any pointers?