Items that do double duty are the ultimate money-savers. Look for stroller/car seat combos, playpens that also function as bassinets and other products that serve multiple purposes. You don't even have to buy items that are specifically marketed for babies; this is a great opportunity to be creative! Repaint an old dresser, buy a changing pad to go on top of it, and voila -- you've got a funky and fun changing table/dresser combo!
While planning your nursery, don't be afraid to think long term. If you buy a crib that turns into a toddler bed, you might not save any money now, but you'll thank yourself in a few years. Just like babies, kids are also really expensive.