test = DictionaryVariable.get('2')
print test

def FindPrice(dictionary, idlist):
    price = 0.00
    for id in idlist:
        price + float(dictionary.get(id))
    return price

Prices = FindPrice(DictionaryVariable, IDListVariable)
print Prices

def FindPrice(dictionary, idlist):
    Price = sum(float(dictionary.get(x,0)) for x in idlist)
    return Price
Prices = FindPrice(DictionaryVariable, FunctionThatMakesListofIDs('FileToGetIDsFrom.xml'))
print Prices

>>> d = {'2': '150.99', '3': '99.50', '15': '5.07'}
>>> d = dict((int(k),float(v)) for k, v in d.iteritems())
>>> d
{2: 150.99000000000001, 3: 99.5, 15: 5.0700000000000003}

>>> dic={'2': '150.99', '3': '99.50', '15': '5.07'}
>>> items= ['2', '2', '3']
>>> sum(float(dic.get(x,0)) for x in items)  #pass 0 to get in case id is not there
401.48

get(...)
    D.get(k[,d]) -> D[k] if k in D, else d.  d defaults to None.