models.py

    def _parse_float(s):
        return float(s.replace(',',''))

    def _size_to_unit_of_measure(size):
        # normalize case
        size = size.lower()
        # Not everything is currently split-able on white space, ie
        # there are existing examples of 9oz etc. But I think those
        # are date entry errors and should be corrected
        parts = size.split(' ')
        # surprisingly there are many floats rather than ints.
        numeric = self._parse_float(parts[0])
        if parts[1] == 'x':
            numeric = numeric * self.parse_float(parts[2])
        unit = parts[-1].replace('.', '')
        return (numeric, unit)

    def unit_price(level):
        try:
            price = self.get_price(level=level)
            size = self._size_to_unit_of_measure(self.piece.name)
            return price / self.quantity * size
        except:
            return None

    def unit_price_retail():
        return self.unit_price(level=RETAIL)

    def unit_price_wholesale():
        return self.unit_price(level=WHOLESALE)