Woodz, that would be an interesting statistic and no doubt one the 'kit car' manufacturers would rather sweep under the rug! I have a gut feeling that a larger percentage of Cobras are completed than other kits for a couple of reasons. Whereas the majority of 'hot rods' are show the majority of Cobra owners are about 'go'. Cobra owners tend to be serious about driving their car, and driving it hard. I suspect that translates into a case where they are also more 'driven' to complete the car they started.
But as for 'value', yup, it's hard to beat a used Cobra replica on the market today. Prices are at an all time low and will continue to fall in my opinion. Cheaper replicas have made the car more widely available to a larger percentage of the population. In that respect the Cobra has lost much of the 'exclusivity' it enjoyed in the past. In turn the number of unfinished kits (Cobras) will also go up as the builders begin to realize they can BUY a finished product, in many cases, for the same or even less dollars than they could build their own car for.
Here in Hawaii a few years ago we could NOT legally register our replica Cobras, PERIOD! There were a handful (5 perhaps) that DID own a Cobra (myself included) and through various methods we 'managed' to figure out how to get them registered. As a result the owners of that time frame were very serious about the car, the history, Carrol Shelby, etc. We got together and became politically active and actually got a law passed allowing the legalization of the Cobra and several other 'kit car's' were included. End result: There are many many more Cobras on Island than ever before, alas, the exclusivity has dropped like a rock! All it takes now is a 'check' and a 'whim' to own such a car. The passion is just not the same with many new owners who simply want a 'cool' car. Sometimes I feel like we shot ourselves in the foot getting the law passed...