My baby is now 9 months old and I thought I would just give my 2 cents on what I feel now were the best and worst investments I made.
Best investment... A boppy pillow. First off I bought this in almost perfectly new condition from someone on craigslist for $10. But I think they are around $50 new and so worth it. Why? Great to help with breastfeeding. Even if you're not breastfeeding I also used it to help prop baby up with tummy time. He seemed to like this better than just on his stomach alone. He loved laying on it as a pillow too when he was younger. It supported him so he wouldn't fall backwards when learning to sit.
Worst Investment... A breathable mesh bumper. Never used it. When baby was young enough he wasn't rolling around to need it. As he's gotten older I can't use it because he would just use it to help himself out of the crib. Bottom line bumpers aren't safe! Those crib packages are a waist of money. You won't use the blanket unless you're going to use it to decorate the wall. Buy a a few cute crib sheets and you're good!