Just don't pay a lot unless you can talk to the owner or someone who knows what is wrong with the machine or the conditions it has been kept it. If kept in a damp area, there is a chance that it has internal rust which may require more than general servicing.
Huskvarna, Bernina and Janome - all good machines. If they are a cheap price, chances are, the original owner passed away or is in a nursing home and it's being sold by relatives who don't know the value. I personally have not been happy with my Brother, so you'll have to ask others about them. Most machines lack features you might want, missing pedal or need a complete cleaning (we're talking replacing the oil). I had a local place completely service a serger that had been in a garage for 15 years for about $80. My sister, who is more mechanically minded, did it herself on the Bernina she found for $10.
edited to add: Bread machines are a GREAT buy at garage sales. Most have rarely been used more than 5 times, so you are pretty much getting a new machine that sat around 3 or 4 years (or more). My Mom uses it for all her kneading and just bakes the bread/pizza in the oven in regular pans. I get her a new garage sale one every 6 years or so since she really only needs it for the kneading and proofing. So unless you have special needs - you can save yourself a lot!
Last edited by IAmCatOwned; 07-21-2012 at 08:51 AM.