Sometimes it's best to buy an external hard drive by looking for the cheapest internal drive that you can buy.
Hard drive prices change like the stock market, with many factors causing prices to rise and fall on a regular basis. If you're looking to add a new drive to your desktop computer, and if you aren't too fussy about exactly what drives you are using, here's a nice trick to save you some cash.
Check the prices of bare internal storage for the size you want, but then also check the price of packaged external drives of the same size. You'll sometimes find that the external drive is cheaper! The external drives are typically built using the cheapest option from any given brand's range, but if you're after something big, and aren't too worried about premium performance, then this is a great path to take.
If you buy this drive, you can take it home and crack the case open to use the drive inside as your new PC storage.