If you need to sell it's worth averaging your sales out over a long period of time by periodical sales. Not doing so is by default betting that you can beat the market and sell at a higher price in the future. Maybe so, maybe not. Most people fail at this. The few who succeed post on these forums about their investment achievements, the rest remain silent.
One thing I do agree with most forum posters about is that bitcoins have found a true resistance level around $8 to $11. It's unlikely they will fall much lower as many miners' costs would be higher than the bitcoins they produce. I know I'll get a deluge of responses from people paying 8c/kWh, but those people need to look beyond the shores of North America. Not everyone pays such low prices. If mining were profitable at $5 or lower with current difficulty (as some claim) then we'd still be seeing a large increase in hash rate every week as it's a no brainer to add as much mining capacity as possible with BTCs at $11.
If is profitable around $5/btc if you are paying 11c KWh, but the profit levels are only about 5-15%... Even with profits going to 30% at $5 or $6/BTC a couple weeks ago many miners were dropping out. I think the fact of the matter is that smaller scale miners are more likely to drop out with price decreases and larger scale miners are hesitant of scaling up further their operations on something of questionable stability, leading to the drops we've seen recently in mining.