How badly you want some? If you have more money than since you can make them. You take two 8 round mags. Cut the top off one right at where the taper ends and have it TIG welded to the bottom of another mag. Grind off the ears of the top mag before welding. Clean up the welds inside and out and add a 170 mm STI spring and for about $100 total you have a 12 round mag. Useless as tits on a boar hog but you have your "high" cap that sticks way the hell out the bottom of the gun making it about as "compact" as a Mark 23.
And I apologize to those who are as sick of seeing these pics as I am of posting them, but until the search feature is used more I guess I will have to keep posting them.
This is what it looks like when done to USP 10 round mags which yield a 17 round mag, but the process is the same with the Compact .45 mags.
Again, do these conversions ONLY if you have more money than since. They work fine but are totally useless.