I know the things I absolutely will buy new are the crib/car seats. My daughter is almost 17 months old and even though we paid $200 for her crib through Amazon it's wobbly. I'll be looking at cribs in person this time to make sure it's solid.

I'm buying most stuff used and only my favorite items brand new.

Couponing! I don't do it personally but my MIL coupons & has gotten us a stack of over 100 packs of wet wipes completely for free!