Here are some links to chew on:
B&B
Located in Missouri. Low to mid-cost. Offers kits and turnkeys. Their '5.0 donor' has all new parts other than the drivetrain.
Backdraft
Located in Florida. Offers just a turnkey as far as I know. Priced below $40k I think.
Carcepts
Located in Oregon. Low cost. Offers kits and turnkeys. Fully uses the "donor" concept, taking drivetrain, steering, gas tank, radiator, rear end, suspension, etc. from '87 to '93 Mustang. Can package donor parts with the kit. Complete turnkey is the most affordable in the industry, starting at $20k with donor parts. Can be built with new parts at much higher cost.
ERA
Located in Connecticut. High-end replica. Offers mostly built kits or turnkeys. Really nice car if you can afford it.
FFR
Located in Massachusetts. Low cost. The most popular Cobra replica maker for the last few years. Only offers kits that make full use of the "donor" concept, taking drivetrain, steering, gas tank, radiator, rear end, suspension, gauges, etc. from '87 to '93 Mustang. Aluminum panels make it different from other "budget" replicas. Nice turnkeys available from levyracing.com for around $30k. Can be built with new parts at much higher cost.
Hunter
Located in Florida. Uses C4 Corvette suspension parts. Mid to low cost.
Kirkham
Located in Washington. Ultra high-end replica. Has aluminum body fabricated in Poland to original spec. We'd all have one if we had the money.
Lone Star
Located in Texas. Nice mid-cost replica.
Mid States
Located in Nebraska. Nice mid-cost replica. Offers kits and turnkeys I think. Same as Shell Valley?
Shelby
Located in Nevada. A super nice replica, and officially a Shelby Cobra. Even better than Kirkham, as you can get the same aluminum body plus a CSX number. You'll have to be rich, though.
Shell Valley
Located in Nebraska. Nice mid-cost replica. Offers kits and turnkeys I think. Same as Mid States?
Superformance
Located in South Africa. Delivers complete cars sans drivetrain to US dealers. High-end replica. Again, really nice if you can afford it. No option to build yourself.
Unique
Located in Alabama. Last but not least, especially since you live in Alabama. Nice mid-cost replica. Similar setup to ERA, but at a lower cost.