Hi Cheryl,
I was also looking at the Britax. However, when I asked my friends, they said besides being really expensive, it is huge. They were having troubles fitting the car seat and other passengers in the back of their SUV's.
I just bought the Safety First - Alpha Omega Elite. You might see the Apha Omega Elite, by Cosco. It's the same thing. Safety First is owned by Cosco.
"Designed for your growing child, the Alpha Omega Elite™ Convertible Car Seat features our Quick-Fit Harness System that never needs re-threading and energy absorbing EPP foam. It fits children rear-facing from 5-35 lbs, forward-facing from 22-40 lbs, and as a belt-positioning booster for 40-100 lbs."
It has a base that is detachable if you need more room in your back seat. I had a bit of a hard time installing it in my 4Runner. I am using towels to make it level. I'm considering buying another one for my husband's car because I won't be moving it from car to car. However, once it's in, it's great. My 11 month old son loves going for rides in the car now. It's very comfortable and really easy to get him in and out of it. It's also really easy to adjust the straps for when your little one gets bigger.
I bought my car seat online through Costco. It is only $130. Shipping and handling is included. When I bought mine, maybe 2 months ago, there was an automatic $30 rebate. You can actually look at the instruction book to see all the features and installation directions. I thought it was really helpful to see it before I decided to purchase it.
My friends say they bought their Alpha Omegas at Big Lots. I was hesitant at first, but the store is able to sell it for less because they changed the pattern of the fabric and are selling the new ones for more at baby stores. All in all, I would definitely recommend this car seat.
Good luck!