In Australia, last year the cost of organising a retreat, of having an actual physical centre and land, providing beds, mats, cushions, electricity, water, cooking costs, food, linen, pillows, beverages, etc. for 10 days came to approximately $23.00 per day per retreatant. Which would be about $230.00 per yogi for the 10 days ... with no profit factor. Not to mention that the Assistant Teachers, office staff and cooks are not paid.
So ... though this is not asked for, and it not necessary to pay anything, meditators would do well to remember that the very first thing the Buddha taught those new to his teachings is Dana (Generosity).
---The trouble is that you think you have time---
---Worry is the Interest, paid in advance, on a debt you may never owe---
---It's not what happens to you in life that is important ~ it's what you do with it ---