"Cheap" in this instance was clearly meant pejoratively, not descriptively. Replacing it with "inexpensive", "economical" or "low-cost" doesn't really fit. Replacing it with "tacky", "trashy", "bum", "chintzy", "crummy", "punk" or similar from your thesaurus clearly fits the meaning intended.
And that's all premised on the fact that this plastic casing is even cheap, which we clearly don't actually know. How do we know they didn't try and get fancy with their material selection or manufacturing (like Apple often does) and then blow it (like Apple often does). Did the plastic in the G4 cube have cracks because it was "cheap"? Did the white MacBook suffer discoloration because the plastic was "cheap"? No, someone or something messed up and even with fancy engineers and fancy plastics it wasn't caught in time. Assuming the Droid even has such issues, I'd guess the same cause.
And that's all premised on the fact that this plastic casing is even cheap, which we clearly don't actually know. How do we know they didn't try and get fancy with their material selection or manufacturing (like Apple often does) and then blow it (like Apple often does). Did the plastic in the G4 cube have cracks because it was "cheap"? Did the white MacBook suffer discoloration because the plastic was "cheap"? No, someone or something messed up and even with fancy engineers and fancy plastics it wasn't caught in time. Assuming the Droid even has such issues, I'd guess the same cause.