It might not be made out of paper, but the Alfa bike seems pretty good. Even though its made out of cardboard, its very strong (can support riders up to 485lbs.), fire and waterproof, and only costs $15.
Depends what you want from the phone. If you care about having a good camera, then by all means get the Xperia SP. But for everything else (performance, screen, design, battery), then the Nexus 4. The Nexus will get at least 3 updates so its more futureproof.