Needham, MA Dan Gardner of DMG Brokerage represented SSG Development in the acquisition of 540 Hillside Ave. The property is a 1.89-acre property that was not on the market for sale. Gardner found the property through his exclusive off-market prospecting database and was acquired for $5.75 million. SSG is developing a three-story 123,000 s/f, class A, climate-controlled self-storage building.