Can doing this possibly save money? You can get about 4 months worth of finasteride for almost price of one month of dutas. Might just buy some finasteride with the order and run both.
My own feeling is that a dollar's worth of dutasteride suppresses DHT more than a dollar's worth of finasteride, so I don't see why using the two together would be the cheapest option. To get the most bang for your buck, just put your money into dutasteride alone.