What is the value of a 1985 Elvis Presley error stamp mint from Saint Vincent and the Grenadines never hinged original gum condition?

Depending on WHAT you are considering an error.

The inverted frame Elvis Presley Stamps are worth no more than $5.00 for the set.

These stamps were meant for use as promotional items.

The unissued $4 stamp pair is worth approximately $5-10.00 for a pair as they are limited.