You should buy a good quality walkie talkie with baby-monitor function. Many friends have told me not to EVER buy baby monitors.
One friend bought a baby monitor and as it turns out, it barely sent signal through 1 wall. It didn't work throught 2 walls anymore. In other words, the baby monitor started working when she was close enough to physically listen to the baby cry in the other room. She said she bought the best baby monitor she could find and she was utterly disappointed.
The price range is the same, but you'll get MUCH better quality with walkie talkies. You'll get many miles distance, not just to the other room.
I found this, but I'm not sure if it's the same one 2 of my friends have bought and totally love. https://www.amherst.co.uk/acatalog/walkie-talkies-as-baby-monitor.html Not suitable for US, but there must be similar products for US as well.