I consider that ETH will never drop lower that 200 dollar for coin, so you should buy it right now because ETH shows pretty stable growth last month. If you don't you may regret about whole bunch of missed possibilites, casue I do not consider that ETH is going to fall once more.
It is not gold or oil you know... it can easily drop bellow 200$, even bellow 1$ if the core team decides they got bored and quit... ofcourse that's a bit far-fetched but you can't draw a line at 200$.
There are many good projects which are underestimated and are flying under the radar, when people notice one of the projects which do what ETH does and even better but it's 10 times cheaper to invest in that other project, then you'll see how low can the price of a top10 coin can fall!