Payment to join the community is a far more interesting topic than mats.
I don't believe any of the current members were/are aware of required payment to join the forum.
As for the sparse replies my guess is that this is a topic covered several times before. But perhaps you searched it and didn't find what you were looking for. And, after all, for $4.95 you should get some real-time reply:-)
As for the mat issue it is completely subjective.
There are some instances where a mat needs to be "sticky" and other instances where it that is not important. I personally use a pistachio PER mat (5mm) from Barefoot Yoga. However at the studio we use tapas mats from Hugger Mugger.
Some mats are smelly, others are downright toxic, and some are neither but have nasty stuff in them to begin with.