I just received an email from Ruger. They are offering the Tri-mag connector device along with 3 factory 10rd magazines for $50 ($10.29 less than normal pricing). They are charging about $9 for shipping, so I guess you can consider it a wash. I really like the Tr-mag system.
BX-1-TriMag-Special-Sturm, Ruger & Co., Inc.
BX-1-TriMag-Special-Sturm, Ruger & Co., Inc.