redmt,
First and foremost, welcome !!!
If you want to get an overview of different Cobras in one place, take a look on Cobra Country ...
http://www.cobracountry.com/home2.html
To buy or build is an interesting question ... but as the guys said above, go to some shows and take a look around ... I doubt you will find (2) Cobras exactly alike.
These cars can be had with a top and a heater, don't know of too many that have A/C, but I am sure it's been done.
Best of luck with your quest
