I bought a used instride machine which is like a gazelle and I love it. I use it every day for a min. of 10 minutes. I paid $5.00 for it and wouldn't sell it for $100.00. I have had multiple knee surgeries and it doesn't hurt me at all. I also have an eliptical machine that I like and in the store it didn't hurt my knee but it does now if I use it for more than 3 minutes so I will be selling it soon(hopefully!) I suggest finding one used and see if you like it or not but do give it some time to try it out. Mine has to have the bearings greased once in awhile but that isn't any big thing to me.