Sell out argument was weak for the U2 themed Ipod (and indeed the entire U2 catalogue going digital) when they themed up with Apple, and it's non-existent with Blacberry sponsoring the tour (and, as the band put it, giving them access into their lab to help design the tour).
Speaking of Zoo TV, they did ask Phillips to pay up for the fancy screens. They didn't, so the band had to pay up for it, but they did consider sponsorship. Read Flanagan's book. I do believe they had a sponsor for Popmart, in S. America at least. And there were little "____ (MTV or VH1 in America, other companies in Europe) presents U2" notes on the tickets for Elevation and Vertigo.