I bought this one on Amazon nearly 2 years ago and it has been good. It's cheap and no-frills, but it has held up well since we got it. I chose this model because it has a low deck height and we have low ceilings in our basement.

Good luck!

I’ve bought this one twice. It’s inexpensive but pretty good for the money. Had to buy a new one because I dropped a potted plant on the first one while it was running and the dirt got all up in the motor. I could have cleaned it but got frustrated lol. It was easier to get a new one. XTERRA Fitness TR150 Folding... https://www.amazon.com/dp/B01M0L0D90?ref=ppx_pop_mob_ap_share

I have this treadmill: https://smile.amazon.com/gp/product/B01M0L0D90/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I really like it. It's a great treadmill for the price. However, it doesn't fold flat against the floor like you wanted. It folds up, and the frame at the bottom remains on the floor and sticks out a couple of feet, so the footprint is not as small as you might want. Folding it is easy, but it's also heavy and not super easy to move around; you kind of have to push it like a wheelbarrow which is awkward if you're a smallish woman like me. But I was able to assemble it alone and I can move it alone when I need to.