How much would a really nice example of say a Phoenix cost ? 
And are the other titles like Gorgar, Flash and Firepower the same money, or are some titles of this era much much cheaper ?   

A price estimate and availability of each of these title would help me pls. Must be really nice condition.

Phoenix $ ??
Gorgar $ ??
Flash $ ??
Firepower $ ??

Did you see the Phoenix in Ebay a couple of days ago, it went for $485.
Needed some work but cheap enough.