Why market averaging in ticker websites for cryptos is perhaps bad...

So I woke up this morning to see that my BTG had basically doubled! Wow that was great, that is the coin I mine. So when I went to trade it for a few coins I've been interested in I got some bad news. It was worth no where near what coinmarket cap or coinomi or what cryto market said. Basically this was the first day BTG has been sold on coinone and it is selling for around $415 there as appose to around $125-130 on all other markets. I feel like this should be a huge opportunity for abritage, but something smells funny and I'm basically scared to do it. Anyone have thoughts?