Value (in cents) of big words

I found the answer to this question interesting in that he referred to a "75 cent word". I would have called it a 50-cent word, not because I undervalued his answer but because that is how I have heard the phrase. I thought at first that am old enough that inflation caused the difference, but I found a 1976 reference to 75-cent word from 1976, the earliest reference to the phrase I found in a quick ngrams search.

What is the "right" value to use in the phrase "?-cent word" (or, what was the original)? Has it changed over time? Do non-American English speakers have alternative expressions in local currency?

Checking NGram for cent word, it seems to me the most common usage is Don't use a 50-cent word when a 5-cent one will do.

The earliest example I can find for a 50-cent word is Printers' ink, Volume 153, Issue 2 (1930), where it's not contrasted with any higher/lower value word. But I think it's being used to identify an impressive-sounding new buzzword, so I guess the speaker already knew the 50-5 saying.

Having invented the English language, we Brits think our words are beyond price anyway, so we don't have any monetary idioms for them. We do use tuppenny-ha'penny and ten-a-penny¹ for things that are cheap/low-quality, but there's no standard "high-price" version for expensive/good alternatives.

¹ cf US two-bit and dime a dozen

The origin of this expression was in the days of the telegraph. When you wanted to send a message over telegraph, you were charged per word. The larger the word, the higher the price. So, "fifty-cent word" (or whatever the monetary amount) referred to a word with many letters, probably the maximum price at the time.

As stated elsewhere, the implication is that a shorter, "cheaper" word would have worked just as well or better in the given context!