Car Seats?!?--looking for basic recs now that we're adding a second vehicle

We have an almost-4 yr old, almost-2 yr old and a newborn (yes, it's busy!) and we're getting a second car. In our current car (Ford Taurus), we have a Britax for the middle one and a Graco for the oldest. We have a SnugRide for the infant that I've been happy with. My plan is to get another Snugride for the second car (minivan), but I am looking for recs. I would prefer to get a cheaper car seat than the Britax, but I would consider it if it really is the best. I like it well enough, but I'm not in love with it...
Suggestions? I looked into this a lot with #1 and 2 but am a little out of the loop since I haven't been on the market for car seats for a year or so....
THANKS!!!!!:P
Rebecca

[mommyto4]

What are the kids heights and weights? What Britax and Graco seats do you have now and where are your kids shoulders in relation to the top slots?