@jwalgran @ahinz For helping with storing currency codes instead of actual symbols, we could use https://pypi.python.org/pypi/pycountry

Then converting the code to the symbol becomes:
```
argentine_peso = pycountry.currencies.get(letter='ARS')
```

Storing all currency multipliers in USD seems like far too much work for little gain though.  We'd be showing different numbers all the time for non-US instances.
We should use 1 currency per instance, and only do conversions when aggregating over mutliple instances.