Arbitrage in Peso/Dollar echange rate

does anyone have experience trading to/from Peso/Dollar with the motive of trading profits? This question can also be stated:

1) What are the "markets" where one can exchange Peso/Dollar? Take the Yen for example, one can go to banks, local exchange places, one can trade futures and options on the Yen. The Yen can be traded either in cash (in person) or electronically (instantaneously). All of these markets serve as arbitrage and thus you find an exchange rate with little variation at any given point in time.

My Impression on the Peso/Dollar exchange rate is that different institutions ("markets") have significantly different exchange rates. This forms an inefficient market, and I feel obligated to cure it by taking advantage of it.

Anyone with actual experience? Thanks in advance.

not only is it a highly inefficient market, it is also very illiquid.
when you feel the need to turn your position you might not be able too.
it is controlled by the big local banks, who are better aware than you when the
government is paying large for oil imports.
the spread is alo rather large . the bigger dealers here might also not necessarily
trade with you due to credit considirations.
all in all I think its more trouble than profitable.

Have you tried to trade this for profit?