Which cost more gold filled jewelry or gold plated jewelry?

first question ...do you folks have a preference for gold filled or vermeil? I have heard that vermeil doesn't hold up any better than plating ...?

...also, I have some gold plated pewter that wears off so quickly, I wouldn't dare sell anything made of it ...can I treat it with something to prolong the gold plating? I wore a necklace for a total of maybe 15 hours and the plating wore off enough to make the beads grey & dull ...how can I sell that? I'm so disappointed in gold plated pewter but I'm also afraid plated brass would tarnish so quickly .