What's the best way to explain storage issues to developers and other users

When server storage gets low developers all start to moan, "I can get a 1 TB drive at Walmart for 100 bucks, what's the problem".

How can the complexities of storage be explained to developers so that they will understand why a 1 TB drive from Walmart just won't work.

p.s. I'm a developer and want to know too: )