Yeah, DSA
http://www.dsarms.com/ had used Metric FAL magazines for $7.00 advertised for the last year, although it's not currently on their web site nor in their SGN ad. They don't look great, but they function well. Bought some spare mag springs, just in case.
CDNN (800) 588-9500 has them for $15.
A&D Glogal, Inc (847) 837-8840 or adglobal@aol.com advertises "Austrian Mags, used," for
$7.00 and a quantity discount.
Classic Arms (704)821-6878 advertises surplus FAL mags at $12.95
One-Eyed Jack (818) 879-8026 advertises Belgian for $18.00
Some dealers will charge more for the aluminium alloy magazines, calling them, "lightweight" (which they are, but not by much) or even, "rare" (which they are not). Other dealers will charge more for the steel versions. I have discovered that the aluminium mags will swell somewhat when fully loaded, making them a little more difficult to insert into the mag well. The steel mags will not swell a bit. Some of the steel mags have holes in the back that allow you to see, roughly, how many rounds are in it.
You can tell the metric magazines from the inch-pattern magazines by the hook (that engages the cut in the front of the mag well) at the upper-front of the magazine. The metric hook is punched right out of the mag body. The inch-pattern hook is a separate piece that is brazed/welded in place and is significantly wider than the metric version.
The FAL adjustable gas regulator is pretty cool. You can adjust it down until it starts to malfunction and then turn it back up a notch or two for about the lightest recoil with that load. You can also rotate the gas plug and disconnect the gas system entirely, requiring you to cycle the action manually (why you'd want to do this, other than firing rifle grenades or other odd loads, I don't know).
The FAL has some other neat little features like the rear of the gas piston is female threaded to mate with the pull-through-cord type cleaning kit available through DSA. The guts are super simple and require no tools to remove the hammer, trigger, and sear.
If I'm not mistaken, it also owes some of its design to your friend and mine, John Browning. Yes, happiness is a warm FAL.