Here is some thoughts about why the price is sliding down, and why it will continue to.
1. Silk road has been having major problems. This is cutting the demand for BTC dramatically.
2. Bitinstant has been having problems and, the problems with silk road are further dropping the amount of people using bitinstant. Bitinstant was a huge "push" up for the price, as all of those people were placing market orders.
3. This is less important (imo) but on May 15th we are all supposed to "upgrade" our wallets. Perhaps people are worried about this.
Without SR and Bitinstant, bitcoins are not worth anywhere near $150+
Negative sentiment could be doing it, manipulation could be doing it, fear could be doing it, dumping could be doing, bad news could be doing it, heck, you know what? maybe its a combination of everything. This stuff is impossible to calculate, but if you have an idea of where things are going, profit off it.
I can see Bitinstant as being important, but does SR really mean much?