The bloodbath that's ensued in the weeks since social-networking darling Facebook (Nasdaq: FB) launched on public markets has been well hashed over. It was billed as the biggest winner in the recent spate of tech companies to reach secondary markets, and many expected a veritable feeding frenzy to take place in the days following its first trades, myself included.

Looking back now, we know that's the farthest thing from the truth. A series of missteps caused Facebook to falter on Day One and, even more embarrassingly, to steadily sell off in the ensuing weeks since that fateful day. Facebook closed yesterday below $26 a share (it lost 3.8% to close at $25.87 in case you're interested). This equates to a roughly 30% loss in 19 days' time.

Source: Google Finance.

And while it might seem like this stock's damaged goods, according to one market-beating analyst, a buying opportunity could be around the corner for those looking to pick up shares in this fallen angel on the cheap, or at least cheaper.

One man's trash becomes another man's treasure
Twenty dollars. That's the point where Facebook becomes a buy according to Walter Price, the co-manager of the Allianz RCM Technology Fund. His words should carry some weight for tech investors. His fund, which boasts more than $1 billion in assets under management, beat its technology benchmark over the past 10-, five-, and three-year periods. In an interview with MarketWatch yesterday, Price describes the recent cratering of recent IPOs such as Groupon (Nasdaq: GRPN) and Zynga (Nasdaq: ZNGA) as "a mini-bubble that popped." However, he also said, "Facebook at $20 is worth a look. ... If they execute well, they can go back to $100 billion in three or four years." This implies it'll need to fall nearly $6 further than its current levels, but also that the stock's quickly approaching a vastly more sane valuation.

Foolish bottom line
Although its recent decline might have piqued some investors' interest, I agree that Facebook needs to get cheaper before investors examine it further. Remember, despite the company's reasonably strong growth, it has plenty of questions surrounding the viability of its ad-based business model, especially as traffic increasingly favors its ad-free mobile platform.

Buying Facebook at $20 is effectively half off its offering price, but I'm not convinced it's quite cheap enough. To try to answer that question myself, I'll return tomorrow to try to determine my own buying threshold for Facebook. In the meantime, learn more about the one social networking stock our senior technology analyst favors over Facebook. He detailed it in a recent research report, which you can access for free. The entire social-networking space has been driven down recently, so don't miss what could be a great opportunity. Grab your free copy today.