Recently I was having a discussion with buddy B and he was lamenting the fact that magazines for his Ruger SR9 cost too much money. Buddy N has a rule that any of his first line guns have no less than seven magazines at any one time. I can understand his argument for having so many magazines. You never know when one might go tango uniform on you. One might get lost or stolen, springs and basepads blow out, etc. My other point is that if you ever go to sell the gun, you can use spare magazines as a selling point. Even if you split them out seperately, you will be able to make most, if not all of your money back.
Here's a deal I found for SR9 magazines $29.99 Not too shabby, and free shipping to boot.
For my CZ P-07 from the CZ Custom Shop $40.00. About what I paid for my third one direct from CZ-USA
And for buddy N, who I am preaching to the choir to, Sig Sauer magazines for a P229 $42.00
I don't know if he even has a P229 and I know he buys from someone in Texas, so maybe they give him a better deal.
Like James Rawles says, two is one and one is none. When it breaks, and your in a bind for a replacement, wouldn't it be better to have it on hand than maybe in stock at some place far away. Otherwise you're penny wise and pound foolish.