Don't sell!
Supply/Demand. Basically if the demand is high and the supplies are low, the price will raise. Since this coin has gained a lot of interest, it will likely have a pretty nice demand attached to it, but if the Noble movement continues to move as I suspect, the trading supplies will be a bit harsh, thus raising the price over time. That's exactly why one 42 coin is several 100 BTC, because there are no full 42 coins (maybe now, haven't checked in a while).
Of course you can sell at first sight, but as all good currencies, you should be able to earn more by waiting, if you don't want to keep your coins for noble usages. And of course, I'm just speculating (with some well proved theories as the base for my speculations), and NOBL might start high and crash over night, no one can be sure.