I paid cash for all ds's seats, never used credit cards for one (actually, it's like that with EVERYTHING in my life... if I don't have the money, I don't spend it). His infant seat was a hand-me-down from my mom (I have a little sister who was 14 months old when my ds was born and the carseat was new for my sister). He quickly outgrew that (by like 3-4 months old) and I bought him a Graco ComfortSport for about $100. I wanted a Britax for him but couldn't save up enough money (he was born way bigger than I planned and grew way quicker than I imagined he would!). I moved that one between my car (during the week) and my dad's van (on the weekends since we mostly traveled with him on weekends). It was a pain in the butt! A few months after that I had enough saved for a Britax Marathon. I bought one (paying cash) and put that in my car and the ComfortSport in my dad's van. When ds outgrew the ComfortSport (at about 3 years old) I had saved up enough for a Britax Regent. I put that in my car and the Marathon in my dad's van.
When ds was 3 1/2 we moved to Kentucky. Now the Regent is in my car and the Marathon is in dp's car. Last summer dp's mom was insisting we needed a carseat for her car ("in case of emergency"). She wanted one for quick trips around town or whatever. She was looking at booster seats and was insisting they were fine and we should get one for her car. I refused. DS is nowhere near mature enough to ride in a booster (or big enough, but that's another story.... he's not even 40lbs fully dressed). I ended up finding the Graco Nautilus on sale plus I had my sister with me (who worked at that chain of store so could get a discount) so I ended up getting one since it was a good deal. It now sits in dp's parents garage
BUT I no longer have to hear multiple times a week about how they are going to buy a booster for him. LOL! When ds outgrows the Marathon (probably 1 1/2 to 2 more years) we'll put the Nautilus in dp's car.
I was a single mom until ds was 3 1/2. I had NO help buying carseats (other than the infant seat I borrowed for about 3 months), not even from ds's bio-dad. I saved every single penny my hands came across to pay for them. I went without a lot (I never bought new clothes/shoes/whatever for me and never ate out) so I could save for them. Thankfully we've never had to "test" them, and I pray we never do, but they are worth every penny I spent on them. And I'd do without again in a heartbeat if it meant buying something to potentially save my child's life.