CDNN has them on special this week for $50.  Get them while you can.

Thanks Big-Bore!

Too bad I could only pick up one

Thanks for the heads up. As much as I love my HK I still think the price of the mags is a joke. This week Midway is running a sale on factory 13rd .45ACP Glock mags for $14.99 each.

Man, you missed the boat on the Glock mags.  Last week was when CDNN had a huge blow-out on Glock mags and I think most were around $9.  I too wish HK mags were cheaper but hey, we knew this going in that NOTHING with the "HK" name on it is going to be cheap.  Either you are willing to pay it, even with a little grumbling, or you go Glock.

Are the .45 caliber MK23, USP and USP-Tactical 12rd mags the same or are they each different?

Quoted: Are the .45 caliber MK23, USP and USP-Tactical 12rd mags the same or are they each different?

USP and USP Tac = Same
Mark 23 = Different

Can't use MK23 mags in USPs

Wrong-o.  You can completely use SOCOM Mk 23 mags in the USP.  You cannot use USP mags in the SOCOM.  Even if you put SOCOM base plates on the USP mags so they will lock in the SOCOM they will not feed reliably (USPs have shorter feed lips) but SOCOM mags in the USP are a perfect fit and 100% reliable.  Many of us have been doing this for years over at HKPRO and none have reported any problems at all.  I myself have a dozen SOCOM full caps that I use all the time in the USPs and narry a hitch.  I change out the floor plate to the USP floor plate to get rid of the unsightly gap but that is not needed except for cosmetic reasons.