How much value does a set lose with no instructions?

wickedboarder · 2013-07-04T01:29:15.000Z

Hi everyone, I'm looking to purchase a lot of complete sets, from the early nineties era. Some castle and pirates etc. There are no instructions, at all. The sets are built (from online instructions) and photographed, so I know the sets are complete. I'm just wondering, how much lower than the market value these sets are then worth? is there a percentage anybody uses? do buyers generally care a great deal about the instructions?? Any info is greatly appreciated cheers,