[lamuerteflaca]

Nope, you are wrong. Is a peso sign. http://en.wikipedia.org/wiki/Dollar_sign

[masswerk]

I wouldn't contest this (a pesos being a piece of eight or a Spanish dollar). I would muse, given a 1700 years history of currency symbols denoted by a letter with an extra stroke (or, in some rare cases, as a letter with a hook, like the Florin), it would be a bit strange that the sign for the pesos/dollar would have originated in a totally independent evolution of its own. (The octopus eye of currency symbols?) It seems more likely that a proper sign with a stroke was sought for and the reverse of the coin would have been of some assistance. The "Ps" would have been a different usage, like the concurrent use of "ƒ" and "Fl" for Florin/G(o)ulden, non-withstanding mixed interpretations. (But this is just my opinion.)

[acqq]

Specifically, the US dollar exists only since 1785 and the sign $ was already used before for Peso according to Prof. Cajori who examined the West Indian manuscripts dated 1760 to 1778 http://books.google.at/books?id=4ykDAAAAMBAJ&printsec=frontc...

[wyck]

Here is a $ sign from pre 1700 Spanish coin http://www.ancientresource.com/lots/shipwreck-pirate-coins.h... ( #CS20730 ). There are more of these that pre date that, so this article is fairly opinionated.

[acqq]

And here's the sample of what Prof Cajori presented, a letter from 1778 (that is 7 years before the US dollar was introduced by The Grand Committee of the Continental Congress: http://www.usmint.gov/education/historianscorner/?action=tim...).

http://s23.postimg.org/p1tie5297/peso_as_dollar.png

Thanks to nemo: https://news.ycombinator.com/item?id=9019062