You can buy if you want now, but i would advise you to wait for bitcoin to fall even harder, because you can make more money that way. I think that bitcoin will fall very hard and that one of the altcoins will rise up and take over the place of bitcoin. So you can also invest in some altcoins. Lite coin for an example is the sleeping giant.
If you have a lot of money you must buy bitcoin and then hold for many months and year and sell it when the price of bitcoin was totally high so that you could earn high income. Furthermore, buy low and sell high so that you could earn huge amount of money.