1) Do you agree that a notation should support currency values? That is, they are useful to identify in data, as atomic units?
2) If so, do you agree there should be a single standard symbol and lexical form used to identify them? Because if we don't do that, we have to support every localized notation, correct?
3) If you agree to both of those questions, what symbol do you suggest? ¤ is generic, but not on any keyboard layout I know of. Also, see Chris's note about ASCII priority.
With that background in mind, I imagine the scenario here you have two data in a Ren document which are both the literal $1.00, but one is actually 1.00USD and the other is actually 1.00EUR: it doesn't prevent errors (for instance, when you want to perform an operation like + on the two data), because you still don't know what the data means. You have gained very little over just using the literal 1.00 instead.
So if I were making a proposal I'd be tempted to suggest a syntax like [1.00 USD], and maybe even giving up one of the remaining sigils ^[1.00 USD] if it is important to raise to being a special element in the syntax of a Ren file. Now that you're saying what you mean, you can use the same syntax for all units: ^[1.00 kg m -2] (1 kilogram per square meter), ^[1.00 V hz -.5] (1 volt per square-root-hertz, a typical units specification of noise in opamps).
And while this may be more beneficial in your work, a lot of software does have to deal with money, where it's important not to use floating point, but BCD or something else.
Finnish (/ Swedish) keyboards have ¤ on `<Shift> 4` ($ is `<Alt Gr> 4`).