If you want to go barbell, it can be done fairly inexpensively.

I got this squat rack, it's worked great, and can work with low ceilings: https://www.amazon.com/TDS-Station-Safety-Professionally-Knurled/dp/B00VKGLWUU#customerReviews

Watch craigslist or something for cheap barbell and weights. You can find some deals.

I think you could probably get a setup for around $600-700 that will take you pretty far.

Would a commercial gym be cheaper? Probably, but there is also the convenience factor of not having to travel to workout, to be able to do it whenever you want, and no waiting for equipment.