I agree with HairLossTalk.com, if you're just starting male pattern baldness, propecia may be all you need, and you have time (and hair) to start small and see what works for you. However, if your male pattern baldness is pretty advanced (like mine), and you want to attack it aggressively, use the most you can afford and have time for. Propecia won't eliminate all the DHT in your scalp, so Revivogen can still help. But it may not be necessary for you. The only way you'll know is to use propecia alone for at least a year and see what your results are.
A full-scale assault on male pattern baldness would include propecia, minoxidil and 2% Nizoral. If you wanted to add another DHT-fighter, Revivogen would be a good choice, or you could try something like Fluridil, which is even more expensive.