Buying second hand due to financial difficulties

I'm really having a hard time financially. With my first I spent a huge amount of money buying everything brand new and unfortunately I gave everything away to my sister. I don't want them back, she recently had a baby and she is doing great financially but anyways, I consider everything gone. Recently I came across this Facebook group where parents sells they used baby gear for a fraction of the cost of new stuff. Yesterday I bought a travel system that retails for $400 brand new and I only paid $150. I washed everything with purex and wiped every single plastic with sanitizing wipes, but then my husband made me feel like I made a mistake buying second hand and now I'm having seconds thoughts about using it with my baby. He told me I can totally buy a $50 carseat and then a $80 stroller, both brand new. 
I want to know what people thing about using second hand stuff. Tips, insights, anything. 
UPDATE: Saturday 8/13. I've got a brand new car seat! I purchased a Graco SnugRide 30 so I can use it with the stroller because they are click connect travel system. I used the 15% completion coupon from Target registry and I paid $76!!! I feel so relieved now after reading online about using second hand car seats. Thanks everyone for their input.