Arithmetically scaled price charts are very misleading when the price scales over orders magnitude, as it does in this case. Totally distorts the price movements.
Look at the price on a log scale. Go to bitcoincharts, look at one year of data from Mt Gox or Bitstamp, and click on log scale. Now compare the current run-up to the one that preceded the April crash.
A crash is a possibility, but I don't think we're at the cliff quite yet.
And I agree, it's a long-term buy. Especially if it crashes, whereupon it will be time to jump in with both feet. But if you want to invest in bitcoin, I'm not sure I would recommend waiting for such a crash.
Even on the logarithmic one-year scale we have gone parabolic.