Hilarious - 70% of the enquiries I get are for help with products bought in Envato marketplaces. Sadly, those jobs are rarely worth taking - you can't fix a plugin or theme that is fundamentally broken - but perhaps a marketplace actually run by Envato will foster specialists who specialize in dealing with the problems of specific popular products. You could buy your theme or plugin and then receive an email telling you which freelancer is good at making it work.