I'm not a collector or anything, I just stumbled in here, but I find it interesting that the seller says
"These are the ONLY Corvette stamps ever made."
A quick google image search of ""St. Vincent" corvette stamp" turned up this...

and this...

and this...
And an article in
Corvette Fever about Corvette stamps including links.
A quick search at
carstamps.com shows 40 items found for "Corvette", the most expensive being a $10.95 set depicting Micky Mouse behind the wheel of a '53.
So yeah, that's more than I'll ever actually need to know about Corvette stamps.