A few days ago, when Bitcoin Hardfork was the best time to buy Etherum. That is the time to buy cheap ETH, preparing for the ICO in November.
At present, ETH is still good, you can consider buying it.
Now that it has dropped is still a very good time to purchase ETH.
However, a lot of development is going on and even the difficulty level has reduced recently due to the recent upgrade and I really want to end up seeing how this development will end up turning into for ETH's development in the short term. I foresee it climbing up soon anyway if everything looks pretty good.