How big is the biggest hard drive you can buy? I’m not talking bulk, I’m talking capacity! I’m also talking bang for the buck, or dollars-per-gigabyte.

The first hard drive I bought was a 20MB monster back in 1985. Yep, that’s 20MB. I don’t even think you can find a flash drive that’s 20MB any more. But at the time, 20MB was huge.

You must recall that for years after the PCs birth, programs and data were stored on 360K (yes, kilobyte) floppy disks. So a 20MB hard drive was worth over 50 floppies in storage.

That 20MB drive set me back $220. I bought it from a place called PCs Limited, which eventually became Dell Computer.

The last drive I bought was a 500GB external My Book, for which I paid about $110. That’s .22¢ per gigabyte versus $11,000.00 per gigabyte in 1985 (though there were not gigabyte drives back then). So what’s the most you can get for your dollars/GB today?

For $888 you can get an external, Western Digital My Book 2TB hard drive. That’s 44¢/GB. Most 2TB hard drives run about $220, however, which is 11¢/GB.

I see a 4TB hard drive for $485. That’s 12.125¢/GB. Odds are good, however, that the 4TB drive is really something like four 1TB drives in a single enclosure. Manufacturer’s do that. In fact, most press releases show 3TB drives (single unit) not due out until next year.

Beyond 4TB, you get into hard drive arrays, or drive units that use multiple hard drives either as a stand alone unit or a RAID. The prices are shocking as well: I see a 6TB eSATA drive for $1500, which is 25¢/GB.

Of course, as time goes forward and technology marches on, prices will come down and capacity will go up. Roomy hard drives will become the norm. Then again, perhaps hard drives will go away and we’ll see Solid State Drives (SSDs) replace them for a whole new cost ratio?