The magazine is at the very heart of proper feeding and functioning.
Magazines are assemblies, incorporating different parts which have to function together so optimal feeding timing is achieved.
This is not where you want to cut corners on design, manufacture, quality control, etc.
Ever price Sig, Walther or HK magazines?
The last time I called to order some spare M&P 40c magazines I was told they were awaiting delivery of the magazines from Mec-Gar, BTW. Mec-Gar is known for quality and provides many top quality gun companies with their 'factory magazines'.
I stopped worrying about investing in the best quality magazines I could afford many years ago. It's worth it.
S&W has always provided excellent quality magazines with their centerfire pistols.
If I can save a couple of bucks on new factory mags, or mags made by the same vendor who supplies the factory mags, then I don't mind saving a couple of bucks ... but I won't scrimp and try to cut corners by using something else. (The 1911 magazine market is another story in itself.)
I look at magazines as being replaceable assemblies when it comes to all my pistols, though, meaning they can become damaged or worn in ways that may require replacement during their normal service life. Sometimes some of the parts may require replacement, too, like springs, followers, butt plates or inserts. Once the mag body is damaged or worn, though, it's time to discard it and replace it.
Maybe not for the private owner who lavishes great care on them, and never willingly subjects them to conditions which could damage them in the same manner as when other folks are using similar guns and magazines as regular service weapons.
Magazines are important, though.