I used my plastic computer chair mat until I finally broke down and bought the expensive dot2dance. Dot2dance isn't that expensive, unless you're 5'9 tall like me and their largest size still isn't really big enough for you.
I got my barre on amazon: https://www.amazon.com/gp/product/B07V47Q3D3/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1
Should work for any height. It's very adjustable. The only thing I don't like about it is, because its not very long, you really have to keep your hand and weight in the middle of the barre. If you shift your hand too far forward, it's going to tilt forward. I wish the barre was twice as long just because of that factor, but you're right, it's nice that its smaller so it fits into an apartment. If you could somehow glue it or tie the legs down, then it would be fine. It's a super strong barre, I can put my entire body weight on it, it's just physics that if you get too far to the end of it, of course its going to start tipping over!
There's tons of barre types on amazon. I just wanted something sturdy and not flimsy since I'm a tall girl with a decent amount of weight behind me.
The zoom classes were better than I thought they would be. But I don't envy the teacher. Just trying to watch 10 different kids, all at different camera angles, is a nightmare!
barre: https://www.amazon.com/gp/product/B07V47Q3D3/
There's lots of other choices on amazon. This one is strong enough you can hang your weight from it, but it is really easy to jerk towards you if you're falling. So it's not as good as the much heavier barres in my school.
https://dazzledistributors.com/products/dot2dance-portable-dance-floor
I've got the enormous size and it's still not really that big since I'm 5'9 tall. But it is BIG in the sense that I cannot fit it into the trunk or back seat of my car because of its circular shape and it doesn't fold up. So if you want to transport it anywhere besides your home, you'll need an SUV or a truck or something. If you have flat flooring instead of carpet, it's much cheaper to buy a roll of marley flooring and pin it to the flat floor. Dot2dance is great if you have carpet or grass or something that you want to put it on.