The Glenfield 30A is the same gun as the Marlin 336, except it's got a cheaper piece of wood for the stock and I think less refined open sights. Very nice rifle, but, the 336 is usually on sale for a pretty reasonable price. Unless he's willing to cut you areally good deal, I think I'd pass and get a new Marlin with a factory warranty.
http://www.faqfarm.com/Q/What_is_the_value_of_a_Glenfield_30-30_Model_A