Inexpensive harness or booster for nanny's car?

[bcafe]

My DD just turned 5 and grew out of her scenera--~41#. I am hesitant to booster her just yet, although I will probably get the Sunshine Monterey when it comes out. Are there any inexpensive harnessed seats that have a high weight limit out there? The Graco nautilus is probably more than I would like to spend for the nanny's vehicle. Thanks much!
Betsy

[Joolsplus2]

The Cosco Apex is a little cheaper (www.albeebaby.com may have the safety 1st signature biltmore...same seat... for under $90, though)...it DOES require a headrest or tall seatback behind it, though... if that particular car has that, it's fine. If not, I'd sort of look at the Britax Parkway...I know it's just a booster, but it's very 'wrap-around' and extremely easy to use properly, and on sale at a lot of places (I think?) for like $60.