Received my Costa Ludus / 21st Century Gunfighter "Catalyst" extended mag release for the Smith and Wesson M&P handguns today...
Promptly installed it in my M&P 9mm and can say that despite being a just small light piece of plastic, it's almost worth the $30 it cost shipped to my door. The price is indeed a damn bit absurd but it's also the only extended mag release for the M&P and there are also only two vendors selling it on the Internet right now from what I've seen, so they can pretty much charge whatever they want for it and if you want one, you'll pay it.
So what's it look like installed?
I have read questions from others here asking if it interferes with the use of Raven Concealment Phantom holsters or Comp-Tac MTAC holsters. I carry with both and the holster's trigger guard stops short of the mag release area so, no - it does not interfere and use of those holsters does not cause the mag to eject by accident.
I also tried it with my TT Gunleather and my Occidental Leather Company IWB holsters and it worked just fine with them for the same reason.
Overall I am very pleased. The extended release allows me to drop the mag without breaking my primary hold on the firearm. I have short little Shrek fingers anyway, so this is a huge improvement for me. It's very similar to the Vickers Tactical extended release for the Glock series and I love that on my Glock 19, so... this is a winner.
I'd like to buy about three more of these for our other M&Ps but that'd be nearly $100 in plastic and I'm not about to do it. I may pick up one a month for the next few months, but the price seriously is out of line and out of reach of most people I'm afraid. Which is a shame because it is truly a damn good upgrade.