Good morning

I already have my bike trainer and I want to add a treadmill to my basement.

I had treadmill in the past, I bought one for $50 from craigslist, but it was damaged at the move and I had to let it go.
I cannot say was it accurate, or comfortable, - it was a little flimsy and loud. But I myself never got into the treadmill running,
it was used mostly by my wife who likes to have an option to exercise at home.


Here are the options I have:

- Buy the same stuff from craigslist for $100

- Buy better treadmill from craiglist for $500-600 - I have seen some Nordic Track, Nautilus, Sole

- Do not buy anything, but get fitness class membership

The treadmill is for me to train and for my wife, who just wants to be in shape

What would you recommend?
Is there any brands/models I have to stay away from?


Thanks!