How do i instantiate a class_name passed via cmd line

[Veek. M]

I'm writing a price parser. I need to do the equivalent of perl's
$$var to instantiate a class where $car is the class_name.

I'm passing 'Ebay' or 'Newegg' or 'Amazon' via cmd-line. I have a module 
named ebay.py and a class called Ebay (price parser). I do something 
like:

\> main.py ebay motherboard

and this does: 
 module = __import__(module_name)
but now i need to instantiate the class - right now I do:
 instance = module.Ebay(module_name, product)

how do i replace the 'Ebay' bit with a variable so that I can load any 
class via cmd line.

class Load(object):
    def __init__(self, module_name, product):
        try:
            module = __import__(module_name)
            instance = module.Ebay(module_name, product)
        except ImportError:
            print("Can't find module %s" % module_name)