I think as as a third place it comes without saying that these forums are a great "third place". Besides there forums, I think it very much varies on your interests, where you live and the like.
For many males who are interested in sports, I think your local sporting club is a great third place that is definitely affordable and practical. Your local sports club is a great place to socialise, meet new people and bond over a common shared interest and grow your relationships with people whom you share things in common with. Another good third place for men is the local men's shed. This is a great affordable and practical way to socialise and talk about issues concerning men in a non-judgmental environment. Men's Well-being is also a great open ground gathering for men from all walk's of life. There are also great online social communities/groups on facebook and other social media platforms where you can share experiences and feed off each others energy and passion for interests which you all share.
I know that there are heaps of affordable and practical support groups for women also. I know that Women's Cottage and platforms such as Meetup are great services that facilitate this movement. On these websites you will see groups that all women can be apart of and they are extremely affordable. Some examples of these groups include "Women Get Shit Done" (excuse the French :D), "Sydney Women Empowerment Meetup" and the like. These are amazing supportive groups and you can find these types of group in every major city as well as in rural areas.
I am sorry for my limited knowledge on options available for women as I am a male and I don't want to type things that I don't really know too much about :).
Lastly, phone your local council or communty centre and they will always have information about what is going on and what supportive groups are in your area. There are great, locally run programs that support your community and are extremely affordable, often free and is a great way to build networks and socialise with people in your local community.
Hope this helps people.
All the best!