[SCOBRAC]

I bought my car the way you are. As it happens a little knowledge was a good thing. If I knew what it was when I bought it I would have likely given him more than I did.. Knowing nothing, or next to nothing about the maker can be a good thing.. It was a little more than what you are paying but as it turned out it was probably worth three times what I paid.. Of course I needed to improve it so I have pretty much doubled what I paid for it. Even so it will be worth a good deal more than I have in it when it is done.

Assume the worst.. Find the lowest priced Cobra you can and compare them.. Is your car better? Likely if you can do this more than a couple times you will get an idea what they are selling for.
Another simple way to determine value would be to put a price on each component, engine, tranny, rear end, fiberglass body, frame. If the value of the parts put in a pile is about equal or more than the price you are paying for the car you will likely come out ok.. Assume 2000 hours for a "from scratch" build.. Put a price on that.. That is the "cost" (maybe not the value, but what it would cost to build your car.. If your time is valuable 10k is cheap for a running car..

There are very few Cobras that can be built for under 15k.. Factory Five might be the best example as they use a Mustang 5.0 donor.. You take the price of the 5.0, allow for reselling the unused components, figure about 8k for the kit depending on the options.. You can probably build a running Factory Five for about 10k, plus your time, that doesn't generally allow for rebuilding the engine or tranny but if you invest more in a newer doner those things aren't likely needed anyway.

You couldn't build a Contemporary or an ERA for less than 50-55k and likely you would have more than that into it when done. Other Marques fall in between depending on whether you build a big block or small block, Ford or Chevy...

Shelby wanted to use a small block Chevy when he started.. You can build a nice 350 chevy for under 3k.. An original 427 side oiler can set you back over $10,000. for a used running example and as much as $20,000 for a 550hp example. New 427 aluminum side oilers from Shelby American are $35,000. By contrast a 502 Chevy crate engine can be had for $8500. new.

Good Luck,