Most people tend to knock the A class, however it tends to be people who have never owned one and have heared off someone who says they are not very good...
We had one for over 4 years and it was a great car. I guess depends how much your spending depends what you can get, the faclifted ones (with the mirrors in the indicators) would be slightly better / nicer but otherwise...
As above go for Manual, not Auto or Semi Auto (less to go wrong and autos v pricey when they go wrong)
If it has a sunroof, the full length one check it opens / closes properly and doesn't squeak or leak.
Starter motors very awkard to get to so exspensive to repair but no idea how you check for this.
LWB (long wheel base) models have loads of room in the back.
A140 / A160 probaly as economical as each other.
we had the A210 Evo model and even that with a 2.1 did over 40mpg regulary.
In over 4 years ours needed new Brakes and pads, back exhaust and tyres. Pretty good indeed.
My Brother was so impressed they bought a A170Cdi for his wife, that does over 50mpg.
Model range is either A140, A160, A190, A210 and the A170Cdi
I bought my wife an older one (04) and it did indeed experience the starter motor issue (along with general poor build quality). The original purchase price of £6.5k then ballooned to £10k when all required work was done. It was a great car when all was working but gradually things went horribly wrong and we chopped it in for a Honda.