Prior to the Spanish-American War, the Philippines were something like a 'crown jewel' for Spain; I don't really see them selling it. However, there might be a possibility for a German purchase following the Spanish-American War. If the Spanish were more lucky in this conflict and able to at least secure a draw, they could have held on to that territory. The ensuing financial difficulties of the Spanish state in the aftermath of the war might then nevertheless have forced them to find a buyer for some of their oversea territories - including the Philippines.
And in such a case, Germany could have stepped in.