If you can get yourself to Thailand and dont have an aversion to Buddhism there are Buddhist temples where you can go stay. Frequently you make a donation at the end of your stay with the amount being at your discretion.

An example near Chiang Mai in north west Thailand https://www.fivethousandyears.org/

Also look into Christian monasteries near you. I'm not Christian but spent a silent weekend at a Cistercian monastery and it was amazing. They suggest a donation but there's no charge. Only have to schedule a month or two in advance.

It depends on the season too. During Christmas and Easter, there'd be way more people than at other times

Why not just book a relaxing airbnb?

I suspect that people are looking for something more structured. For that matter, just go on a backpack someplace that doesn't have cellphone service (or just leave your cellphone in the car).

Why go to a gym, when you can CrossFit with random street trash?

I'm not sure what your point is, but I certainly wouldn't compare airbnb to "random street trash". The quality does vary, but if you're careful you can get amazing places.

"GrossFit".

The Vipassana silent courses put on by dhamma.org are entirely free, run by volunteers. The popular locations are fully booked months in advance, but if you have a very flexible schedule you can get on the waitlist and be accepted right before the course, that is how I did my first one.

I've done two 10-day courses from them. After my first one I described it to people as like being in prison, never having gone to prison, but with less freedom than prison. But I still went back for a second time :)

I highly recommend Vipassana too. It completely changed my perceptions about the world and humans.

Goenka’s 10-day vipassana retreats are not only free, but (at least when I took it) they would not even accept donations from those who hadn’t yet experienced the course: https://www.dhamma.org/

There are non-silent Buddhist retreats. Deer Park Monastery etc.