Few of the big liberty hating governments (China, US, EU etc) raid bitcoin exchanges, businesses, sites etc..
(...)
but I think enough people would start buying at the low price
They would buy how/where, with exchanges, businesses, sites etc all being taken down?
Sure, tor exchanges, p2p, irc, and other alternatives will appear. But it's gonna take a while to fully replace the current exchange-based trading environment.
In the mean while, what's gonna happen.. Crash because everyone panics, or skyrocket because bitcoins are now even more difficult to obtain (hence less supply, hence higher prices)?