Depending on where you are there may be an organisation that manges playgroups, for example, our playgroup is a member of playgroups victoria, I think it also has something to do with the baptist playgroup organisation. It is not relegious as such, they have it at the church building, and they share some of the equipment with the sunday childrens program, but they are separate, although they do celebrate Christmas and Easter etc.
Playgroup is a really cheap option, ours is about $30 a term. Other things are a lot dearer. We also do swimming, which is about $120 a term and we were doing ed gym (gymnastics for 3+) which was $7 per week paid for a term in advance.
I really liked playgroup, but try a few. Ours had a lot of structure, but others didn't. I liked the structure, and the kids are young and seemed to respond to it. There were transitions from "free play" to reading a story, then washing hands for morning tea, and then music finished off the session. Similar structure to kinder but not nearly as strict as the kids are too young. They had heaps of different areas of toys, for example they may have a playdough table, a house corner, craft corner, baby corner, book corner, train corner, puzzle table and so on. Mums are free to get a cuppa and have a chat, but are responsible for their own children. To give you an idea, there was 1 1/4 hours play, followed by a story, (while mums pack up toys) morning tea, music and home.
Hope this helps, but know that different playgroups run differently, and ask other mums for their suggestions.
Jodi