AIUI, the game counts how many artifacts and relics your party receives, not how many it has. Once you hit the limit, a flag is set and the game won't give you any more no matter what you do. If you sell any of them, the game won't replace them with others.If you want to download one of the savegame editors (link below) you can both alter the artifacts etc. that your party has (move them into the backpacks first!) and change ordinary items into new artifacts & relics. But if all you want is more gold, it's a lot easier just to use one of the editors to change the amount of gold the party has.
