The original mags are not that hard to find.
A member here on the Forum just sold 27 OEM S&W mags for the model 5904 (and its brethren) for $15.00 each, RIGHT HERE ON THE FORUM CLASSIFIEDS!!!
WITHDRAWN...45 magazines for sale
I know it says "45 Magazines".
That's how many he had.
Check out the link.
He sent me pictures of the mags he had for sale.
He's a nice guy and he had great prices.
If I didn't already have plenty of the mags I collect, I would have bought a bunch myself.
It pays to read your Forum Classifieds.
John