Money Tree?

We went this morning to have all 3 car seats checked. We moved the girls to the back row, and put Joshua's car seat in the middle row, and took out a captain's chair so that the girls could easily get to the back, and we could easily get them in and out. Well, the CSI (car seat inspector ;) ), looked at baby's car seat first. They have already become more high tech in the past 4 years. There was a knob to turn to make the seat level that we didn't have on the girls' Graco Snugfit's. Crazy. So, he adjusts baby's and it was all set. The girls' were more tricky, because they've been in them for 3 years now and so the straps had to be checked and everything else. He gets them all set, and they are all buckled in and we are about to leave when he calls the fire marshall over to double check...this is where I freak out (inside, no waterworks with everyone there)

Their convertible car seats are good until they are 40 lbs. The girls both weigh 33 lbs. They gain about 3 lbs. a year now...so I figured we wouldn't have to buy boosters until they were at least 4 1/2. Well, the fire marshall looks and she says, "You need new car seats, and they won't fit in boosters yet" WHAT?!?!? My girls apparantly are too tall for their seats. She told me there is a car seat that is a 5 pt. harness starting at 20 lbs, and turns into a booster when kid reaches 40 lbs. BUT, that's 300 dollars right there for both of them. We have had SO many expenses come up that we weren't expecting. It's freaking me out so much. Then, in 3 weeks we are going to have an astronomical hospital bill. Seriously, where is the money tree I so need to visit?? Ugh...