Had I been paying closer attention to this, or been thinking more like a 'shark', I'd have run to any local retailers who didn't yet adjusted their prices and buy every hard drive I could see. Interestingly enough, Walmart has already removed all 3.5" internal HDDs from their web site, leaving only SSDs and external HDDs (which of course either contain a standard 2.5" or 3.5" internal HDD with appropriate external interfaces and PSU). However, the external HDDs that do remain have all gone up in price, with most sold out.
Many retailers profited from this unfortunate experience, you can bet on that. Their existing inventory instantly sky-rocketed in value. Many may be holding onto inventory until the market stabilizes and prices are set.
If any of you wish to profit from this, go find any local retailer who isn't keeping up with things, and buy up all their hard drives

. Of course, with darn eBay seller fees, and the trouble of selling crap, you'd need to find a good stash of them to make any real money. For me, I don't have the capital or time to muck with doing such -- but for anyone who does have free time on their hands and enough capital, there you go

.
Similarly, if you have any used HDDs laying around, now is the time to dump them on the market. You never know who might be desperate to find an HDD in this shortage.