Personally i find it very difficult for ethereum to go under $600 because even in the darkest time we had couple of days ago , it bounced back from something around $650. Ethereum stands on a strong basis now so it's much harder for it to go down compared to other alt coins. I think it's a good time to buy ethereum anytime. It will in a much better condition in the near future. It will probably grow faster than bitcoin so if you are looking for a safe and profitable investment , ethereum is the right choice.