Some analysts believe Apple may have sold close to 1 million iPad 2 units during the tablet’s debut weekend. Leading up to launch day, opening weekend sales estimates ranged from 300,000 to 600,000 units. Following nationwide sell outs, however, some analysts have upped their estimates significantly. “We would not be surprised to see Apple sell closer to 1 million iPad2s in the opening weekend,” Wedbush Securities analyst Scott Sutherland told Reuters. Apple Store locations and third-party retail partners across the country ran out of iPad 2 inventory quickly following the tablet’s 5:00 p.m. launch on Friday. Some Best Buy locations claim to have sold out of iPad 2 units and accessories within 10 minutes of making the tablet available to customers. Regarding buyer breakdown, Global Equities Research analyst Trip Chowdhry believes 60% of iPad 2 buyers were upgrading from last year’s model and the remaining 40% were first-time iPad buyers — and he believes 100% of iPad 2 buyers own at least one other Apple product. Chowdhry also thinks people preferred AT&T’s 3G model over Verizon Wireless’ iPad 2 because AT&T has better customer service.