Hey--just saw your reply.
Here are my recs:
Britax Parkway SG--it is a few dollars over budget, at $107. The main thing I like about this that puts it above others is the slide guard--which is a clip/loop that goes over the lap belt to prevent the child from submarining (sliding out under the seat belt in a crash). It's not necessary with bigger kids, but it's a good idea with smaller kids.
Sunshine kids monterey--around $100--you can get it for a little less if you look around
Graco turbobooster--It's just around $40, so obviously the best buy. If you buy this, it comes with screws that you must screw in the armrest before use (the manual will explain).
Re: Sarasmile