As a note, the drives that are usually in external enclosures are pretty much bottom of the barrel. You might not get ANY usable warranty on them (they're usually "OEM" drives, so the warranty would be from the external unit maker who will probably not honor it if you tear the drive out of the enclosure), and they're usually some of the slowest models available. They do store data, though, so if you don't care about warranty or speed, they can be a good deal.
When win 95 came out they were selling 4MB sticks at $100 each. Before that they were a heck of a lot more. I had a 486 DLC and simms were $100 a mb. My point was that SSDs given the right exposure will be embraced by the public as a viable storage facility, while HDD stocks are at these ludicrous prices, which will reduce the stranglehold on the data storage market that magnetic drives have. Yes I had a full height 2gb drive too which had to be replaced several times due to failure. Yes memories....
I see what you're saying. RAM was already getting cheaper fairly quickly, but yes, I do recall that the prices took a substantial drop near when Win95 came out. There was a similar phenomenon when Win2k came out and also WinXP.
What I'm trying to say though is that, while users with modest (which is probably typical) storage needs can and probably will go SSD soon - if they haven't already - since they don't need the additional capacity offered by revolving metal and can then enjoy the benfits of SSD, users who have large data storage needs will probably stick with revolving metal for some time. This isn't to say they won't ALSO have an SSD, but I think it will be quite some time (if ever) before SSDs as we currently know them will overtake revolving metal and other magnetic storage means in terms of bytes per dollar. Advances are still being made in the magnetic arena, and there are currently some problems preventing huge density gains in Flash technology (but I'm sure they'll be eventually resolved, as these things usually are when it comes to semiconductors).
What may happen is that these users with "large" storage needs may not see their needs grow at the same rate as the storage technology does, so they may slide along the curve until SSD or other non-magnetic means make sense for them i.e. their previously "large" needs will become technologically "modest". However, I think users who are continually pushing the envelope in terms of volume data to store and who don't have large performance concerns (which, incidentally, describes a "cloud storage" provider pretty well) will stick with revolving magnetic metal for quite some time. Current SSD technology has almost two orders of magnitude to make up to match revolving metal HDD technology in terms of bytes/dollar, and like I mentioned, HDDs are not stagnant.
Economy of scale in the SSD market will surely help, but it's going to be several years (again, if ever - several years is more than long enough for major technological advances to totally obsolete a storage mechanism so we could have e.g. holographic optical memory by then) before Flash SSD technology will be able to completely replace revolving metal hard drives in nearly all applications.
The biggest thing happening now is simply that most users don't need to store 3TB+ of data. If you've only got 120GB of data, there's little reason to NOT buy an SSD at this point because they don't even make hard drives that small anymore, but if you've got 100TB, there's little reason not to put it on revolving metal hard drives unless you REALLY need absurdly fast access to it. Consider that 100TB is a relatively modest amount of storage for an enterprise in some market segments.