Reminds me how my mother used to say that we’re not rich enough to buy cheap things. I think it must be some proverb somewhere, but I only ever heard it from her.
And what makes things hard is that sometimes the cheap one is good enough for use you will ever get. Think of something like home renovation tools. Doing thing one time, even if badly might be enough. Not that nicer tools wouldn't do it faster, easier and better. Though price difference can be huge.
I was curious and decided to check - there’s Wikipedia page about it. Looks like it Pratchett wasn’t first and took from general wisdom but that specific anecdote was popularized by the book.