Actually all Nordic Track ski machines are discontinued....the company went out of business several years ago. I think Sears carried a line of Nordic Track treadmills or something....but these aren't a real Nordic Track..they just bought the name.
I love mine. But it seems like a real love it or hate it machine. Some folks just don't have the coordination that you need for it....there's just a certain motion to it that if you can catch onto it is great, but some just can't. Of course I've been referred to as a klutz on several occasions and have no problem with it. Its weird. My aunt who was once a very good gymnast couldn't get the hang of it.
For free...give it a try. Mine cost me over $400....but I had used one in a gym before and knew I loved it. A few tips-
If the tension is too loose you'll fly off...if its too tight you won't be able to do it at all. I've been keeping mine at 3 1/2.
Don't do the arms for your first couple of sessions...get used to the leg motion first.
Don't use the incline feature (if the one your getting has it)...you'll slide right off the back!
Once you start with the arms, keep the tension light. Just the motion of your arms will add a kick to the workout without any additional resistance. Add tension as you see fit.
The best thing I ever did was to hunt down a book holder for my Nordic Track.....it holds a book, water bottle and a walkman (never use that slot) and it makes the workout go by so fast to just read a book! And, hey, if anyone has an extra knob for the bottom (where the thing folds) I'd be happy to take it off your hands. Mine broke. Luckily I can still use it w/o a problem.