The easiest thing to do is go to the Almighty Google. Type in the model and year of the vehicle along with MSN Autos. If it's over a couple of years old there will be reliability ratings and user reviews.
This is the very best way to start your search.
Once you find something you are truly interested in... take it to a mechanic and have them do a complete inspection. If you are a layman and not a mechanic then this is the best money you can spend. You may "lose" $50 up front but it will save you many multiples of that by knowing what to expect in repairs down the road.