"Costs a pretty penny"

Question

I have read "costs a pretty penny" before.

Is it okay if I instead use "costs a pretty dollar" or "costs a pretty yen"?

Answer 1

Well, you can say anything you want, but the more remote or non-standard it is, the less likely you'll be understood. I guess that's almost too obvious to say. However, if you said costs a pretty dollar, you might get an askance look from people :-).

Pretty penny is an older colloquialism. Old enough that it is trite.

If you said that costs a pretty yen to me, I'd ask you "well how are things in Japan these days?" :))

Answer 2

Pretty penny is a fixed phrase. The relevant sense of pretty is now listed as "archaic or dialectal" in the OED:

Considerable in number, quantity, or extent, as in a pretty deal, while, way, etc.
. . .
Now arch. or dial.

We still use it with this meaning as an adverb, but not as an adjective. We say a movie was pretty good, but we don't talk about having ^#a pretty dollar.

The relevant meaning of penny is now obscure. It doesn't refer to a single physical penny; instead, it represents a sum of money more generally. The relevant sense from the OED:

Used as a general or vague word for a piece of money; hence, a sum of money, money.   Now chiefly in [the phrase] a pretty penny . . .

Combine these two senses, and you get a phrase pretty penny meaning a considerable sum of money.

However, speakers of today's English don't understand these senses of pretty or penny. We don't think of the phrase pretty penny this way. Instead, we treat the entire phrase as a single vocabulary item with a fixed meaning. Because this is true, you can't build similar phrases using these senses of pretty or penny. And as a result, your examples sound at best like wordplay. At worst, they won't be understood at all.

---

In this answer, the ^# symbol means that the utterance, while not ungrammatical, fails to express the intended meaning.