$18K sounds about right to me depending upon what you want to do and the cost in your area.
I won't even get into the NCRS vs Custom issues and personal debate. I'd put that into a "religious" discussion. What I can say is I feel strongly both ways
With respect to starting price on the car... I paid a premium for mine to get a one owner Texas car. My thoughts were it had all the options I wanted and I knew it only had one bubba working on it before me. I had visions of NCRS survivor status. I spent 2 years repairing saftety items such as suspension and brakes working my way to Engine, Trans, and Cosmetics. Now I've thrown in the towel and decided to make the car my own.
The other thing I learned is that what I love most about the Vette is the actual working on it. There is nothing I enjoy more than the time I spend turning wrenches, cursing frozen bolts, and generally getting myself in over my head.
I agree that organization is the key. I start every section digging into CAC archives, reading project articles, looking at the assembly manual, and thinking.
Regarding price. Labor savings to me are just justification to buy new tools
I have a very high level budget for big items.
Engine $6,500
Trans $3,500
Side Exhaust $2,200
Paint $7,500
Strip and Coat Frame $1,000
Brakes, Suspension, Interior, Lines, Soft Top, Chrome Bumpers, Weather Stripping, Wiring, Clips, Bolts, Etc.... (I probably have $5K into about half of this stuff over the last 2 years and still probaby have $3-4K left)
Add that all up and you've easily got $30K.
Once you go that far you ask yourself "Why am I doing this?" I guarantee you it isn't because you plan on selling it to make money. Sure you can get the car painted for probably half the price, and yes a polished Edelbrock crate motor is much more expensive than rebuilding your existing motor, and of course rebuilding the Muncie for $500 is much cheaper than a new 5spd. A little elbow grease and some POR-15 will give you a very nice looking frame.
Look at your car and ask yourself what you want it to be. If you just want to pull the body to clean things up you can do so without spending a lot of money. I'm still at the point where I can go low budget and be happy that I got some work done. I'm also at the tipping point where I can go all out. Now's the time when my wife is watching me very closely.
Good luck!
Whiplash