I found two AMT 1/16th model Cobra kits currently on eBay.
Auction #3301807924427 ends in just under 1 1/2 days and is at $15.50 USD. Note the ending three digits of this auction!
Auction #130169108201 ends in just under 2 1/2 days and is at $9.99 USD.
A company called MPC originally made the tooling for this kit and sold it under their label. The company was purchased by AMT/Ertl and they sold the same kit with their name on it. Ertl also put this kit out under the label ESC, which I believe was for export. I have at least one of each version, unbuilt, in my collection.
The Ertl factory outlet store in Dyersville, Iowa is a magical place!
Any type of toy they make, from pre-school to adult miniature soldier figurines can be found there. I get there every couple of years and always find obscure stuff that never made it to the stores in my area.
Evers General Store (retail and mail order toys of many brands with lots of diecast, models, and farm toys) located in downtown is good too.
Good luck!
Fast Farmer