GPS UNIT FOR YOUR CAR
Extra cost: Up to $450
Instead: Use a GPS app. Phones that run on the Android OS have one built in; for an iPhone, download NAVIGON MobileNavigator ($50). Then attach your phone to the dashboard with a window mount ($20). Ready to roll.
2-D TO 3-D CONVERSION
Extra cost: about $50
Instead: This feature on Blu-Ray supposedly makes regular movies pop like 3-D. But conversion technology doesn't work very well, says Jerry Del Colliano, the publisher of Home-TheaterReview.com. His advice: "Go native 3-D or don't go at all."
BUILT-IN 3G FOR TABLET
Extra cost: about $130
Instead: If guaranteed uninterrupted web surfing on the road isn't crucial, buy a Wi-Fi-only model. Not only will you pay less upfront, you'll save $15 to $20 a month in 3G fees. Wi-Fi connections are plentiful and, increasingly, free.