Buying a used bike...a few questions.

Well this will be my first Mountain Bike in years and it will be my first serious mountain bike.
I'm currently looking in the sub $1000cad level and most likely will buy something around
2 years old since I will end up with a better bike for cheaper.

What should I look for when buying used? (I'm trying to find bikes with little wear like from people
that bought a nice bike and then lost interest).

Would it be better to buy a lower end frame with high end components that might be slightly
more used or something with a better frame and a mix of components mostly lower mid
range.

I am mostly looking at hardtails since they are more in my price range such as the 2001 Norco
Sasquatch and some others but I also found a 2001 Kona Manomano for a really good price.
I don't think I need FS, it would be more of a luxury item since I will be doing more onroad
riding at first until I find some people to ride with.

Thanks for any help.