Is it right, according to the Vinaya, to charge for Dhamma classes? (I'm not talking about donations, but a fixed amount per class one has to pay) There is a Buddhist Centre close to me that charges circa USD8.00 for Dhamma talks, in one hand I don't like the idea of any religion charging people because poor people will not be able to participate, but on the other hand things are expensive here and they need to pay the bills, my country is not Buddhist at all so running a centre here only on donations must be very hard.

So, from a Vianaya and Buddhist ethics standpoint, is that allowed?
Vinaya only applied to Monks. If it is lay teachers charges may be a possibility but as per my opinion highly not recommended. As for monks I don't think they should do this at all. The trustees (Dayaka Sabawa) may do it but again highly unadvisable as per my opinion.

But having said this, I do not like the idea of any charge. Buddhism was taught free of charge and has maintained this tradition through out most of history. 

Also Buddha put much effort to become a Buddha and tough if for free. It is morally wrong to charge for teaching something the Buddha put so much efforts into when we are just teaching what he prescribed.

If you look at https://www.dhamma.org/ you will see a lot of centers all run solely by donation through out the world. So the donation model does work.