Advice Needed please:)

Hi gals,
I am hoping someone out there can give me some advice regarding purchasing a used bicycle.
My mtn bike was stolen a few years ago and so far I haven't replaced it- I am itching to now. The other day DH and I were in the LBS they had a used B1 sitting there- it was about a 1/4 the cost of a new one- the size seemed good.
What I would like to know is where should I look for wear on the bike?- it seemed like too good a deal, they said they would replace the seat and give me new tires.
Thanks in advance:)

Check the cassette and chainrings. Compare the teeth on them to a new bike to see how worn they are. Check the brakepads to see if they are worn down. Check the frame for cracks. If it shifts and brakes good on a test ride you probably are getting a good deal. That's about all my limited knowledge can help with.

li10up's advice is good. Chain, chainrings, cassette and brake pads are parts that wear out and need to be replace periodically, though chainrings should last a long time and could be expensive. Check that the frame is without cracks or dents and no major scratches. Look carefully for any indications of bends in the frame or a previous accident. Look from the front, back, and side to see that things look straight and aligned. Fork blades can be bend backwards from an impact. A test ride is helpful here - the bike should ride straight without a tendency to turn even if you release the bars briefly. Also check the bearings for smoothness and lack of play. Remove each wheel from the bike and turn the axle by hand - it should feel smooth without any notches and it should turn very freely but without any side-to-side play. Spin the wheel while holding the axle ends in your hands - it should keep turning for a long time. Remove the chain from the chainrings (drop it between the crank and the frame) and spin the crank. It should spin freely and smoothly and have no play.

Also a good idea to find out the age of the bike and availability of parts for it.

Thanks for the info ladies- I will go check out the bike again tomorrow- at least now I know what to look for-
Thanks again- I appreciate the input:)