I think I have the same booster seat as you BamBam. I bought mine from Walmart for about $29, about a month ago. It has brown trim, an adjustable back height, folding armests and converts as the child grows. Wow, what a breeze it is using the booster seat compared to a baby seat with the latch system..
I agree with Axis, the booster seat is pretty basic compared to an infant/toddler car seat. I would go to Walmart or Target and get one that is on sale for around $30. One thing to note, I would buy a neutral colored one just in case you need it again one day for another kid, plus it would be easier to sell on craigslist once you are done with it.