More than $300. to upgrade to the 900 when you factor in what you paid for the 800 and what you will get on a resale, and especially since the market may be flooded with them.Coin shooter I have a nox 800 to get new bells and whistles it's more than $300 to (UPGRADE) AS to the 800 leaking and get a 900 in trade I think they well have a upgrade for the nox 800 a plastic bag $ 150.00 to your door from minelab. sube