That's really true of the early Corvettes as well. Although big auctions like B-J and the like have had inflationary effect on early Corvette prices (too many bidders with more money than brains--and often even bigger egos), it remains pretty difficult to 'have a car restored' (ie: pay someone else to restore it plus find/supply the parts) and come out even, much less ahead of the game on value. Labour costs are the real killers here and this is where the 'hobby' restorer, who does the restoration his/herself can really win big time, provided the work is of high quality.
Not only does the owner/restorer enjoy the benefit of doing the work itself, with the pitfalls, cuts/bruises as well as the pride accruing from having done a job well, but there will also be a concomitant value increase to the vehicle, which, although not the 'reason' for the restoration, is of some comfort if/when it comes time to sell. This of course is provided you don't factor into the 'costs' of restoration, the value of your own time and labour.
On my own part, I find that my 'blood sweat and tears' expended in restoring my Corvette leads me to unreasonably value the car in emotional terms, but who in the hobby doesn't feel that way? I still find the need for a 'fix' every now and then during the long, cold Ottawa winter and slip out to the garage to lift the car cover and admire the bright red lacquer on fibreglas and dream of the first summer drive... Isn't that what the hobby's all about?