Just considering the general point about charging or not charging for classes. In my centre there is a general principle that all payment is donation or dana. So we are often invited to put something in the dana bowl if we want to. This seems very fair as bills have to be paid if the Buddhist centre is to continue.
Alongside this is the notion of a suggested donation so for a class a donation might be £6/£3 for waged/unwaged but this is only a suggestion. This works very well for me. Firstly it's a genuine offer - it is dana so if you can't pay (or won't) then that is fine. No-one will question that or think any less of the person. But also a lot of people (myself included) want to know what a fair donation is and pay that. I want to be told what to donate. I find it unsettling to be told to pay whatever I feel. I want some guidance.
From a very pragmatic point of view, if it is a genuine donation then there are tax rebates that can be claimed. That is not a major consideration - the principle remains that everyone should be able to access the dharma. But it is another angle to it I think.
But generally I just wanted to put this model forward as (our) way of combining dana and universal access to the Dharma with the realities of running a Buddhist centre.