It is really annoying to hear so many opinions here choosing to believe an alternate version simply because it sounds better to them rather than because of any actual evidence. (Are we still in Hacker News or is it a Sunday thing?) It feels like I'm reading opinions by creationists.
Even the us government agrees that the $ symbol is a peso sign. [1]
Here is the relevant piece:
>>What is the origin of the $ sign? The origin of the "$" sign has been variously accounted for, however, the most widely accepted explanation is that the symbol is the result of evolution, independently in different places, of the Mexican or Spanish "P's" for pesos, or piastres, or pieces of eight. The theory, derived from a study of old manuscripts, is that the "S" gradually came to be written over the "P," developing a close equivalent of the "$" mark. It was widely used before the adoption of the United States dollar in 1785.<<