Recommend a foldaway strider exercise machine?

Not much luck Googling for this, except for Brookstone which has one. Reviews, however, show it is pretty flimsy.

I have exercised strenuously all my life, running for 20 years and mountain climbing for the last 15 years. I am very fit, except for the stupid knees which are now giving out. I tore the meniscus once in each knee some years ago and surgery fixed that, but now a combination of arthritis and wear and tear has made even walking difficult. It does not appear that much can be done other than replacements, which am not about to go into now.

The only way I can get any good cardio exercise now is by workouts where I don’t have to bend my knees. Most good striders are just too big for our house, so really would hope to get a fold-away one that is well built.

Anybody know of one, or am I just crying in the wilderness?