How often do you plan to shoot your new gun?
A good magazine should last for several thousand rounds. Maybe I should just keep my mouth shut, but with all due respect and not to sound too much like a jerk, if having to buy a $50 magazine a couple of years from now is that much of an issue for you, are you sure you can afford this gun?
How about this... every week put a $1 bill in an envelope. You'll never miss it. At the end of a year, you will magically have enough money for a brand new magazine! Now if you can't afford this, I don't know how on earth you will ever be able to afford ammunition for this gun. $50 might buy you 200 rounds of cheap 9mm ammo. Even if you can find WWB's at Wal-Mart, that will still cost you $40 + tax.