Being honest if you really want some bitcoins,
Go and buy now because the price is increasing and maybe you will get a profit in future.
If we/you are waiting for 100 dollars i think that for this year is impossible.
I agree with this growing speed bitcoin's price may reach $500 easily. However I feel that this increase is not stable and long-term
Yes, all bitcoin price not 'stable' for long term. They need a lot event to make "BTC price" going up with streak win.
Sometimes, unexpectedly there are bad event too for bitcoin. So keep follow the news.