Phoenix - Sonoran Rock Investments LLC in Scottsdale (Kevin Reiser, Mark Paliscak, Paul Paliscak, principals) paid just under $1.103 million ($185 per foot) to buy a 5,960-square-foot shell office building located at 4550 E. Bell Road in Phoenix. The seller was a company formed by Randy Stolworthy of RRS & Co. in Phoenix. The sale was brokered through Phil Breidenbach, Peter Nieman and Lindsey Carlson of Colliers International in Phoenix, Megan Sherwood of Plaza Del Rio Management in Peoria, and Lynne Ostreicher of Ostreicher Realty Group in Scottsdale. Sources say the buyer will use the office space to house a mortgage business. The structure is within the 45th Place office project. That nine-building, 104,210-square-foot complex, was developed by RRS & Co. The project is sold out (see related story P. 10).