I have not started any local support groups, but I have been a director of an inclusive homeschool group (2 years), as well as a president of a moms club chapter and a co-leader of a Roots & Shoots group. I have lots of ideas for you and want to be sure to say, "go for it!! yay!" to you.
I think that meet-up is limiting, only because it costs, but it doesn't hurt to try to recruit members using it, if you don't mind the expense.
I think you should start the group using a Yahoo Group. Do you have any homeschool friends who would help you start it up? You should decide whether you want to be an "inclusive" group or a "secular" group. Inclusive means you will include everyone, regardless of religion, type of homeschooling, sexual orientation, race, etc. Secular would be a little more exclusive, asking that members do not discuss religion on the group board or at group events, and not promote religion-only events (ie. a Christian prom).
Once you have a few events in mind, perhaps a weekly park day (something you can commit to being at for at least a couple months), an educational field trip, a craft or game day, or other things that you can come up with that will be attractive enough for people to WANT to go out on a limb and go to your events, regardless of whether or not they know anyone.
Next, advertise. I suggest printing up flyers and giving them to your area children's librarian, asking to pass them out at local teacher's or educational toy stores in the area, at gymnastics businesses or parks & rec centers, etc. Put your first few events (anything not hosted at a private home) in the free calendar sections of your local newspapers, community newsletters, and in any free parenting magazines that are available in your area. Consider getting a free phone number (Google voice?), if you can, to use as your group's number, as well as a dedicated email address that you will check frequently. Make the Yahoo Group private and only accept members who explain to you who they are (homeschoolers, not businesses looking to promote).
Perhaps after you have a few events and have 4 or more members, you might consider hosting an "Open House" and advertising it as hard as you can to the members of every homeschool class in your area. We love using community center rooms for small fees for events like that, then have our members split the small fees to help promote the group.
Once you have enough members, you will want to decide upon some rules. For instance, you might decide to write up some bylaws. You might make the rule that to be a member, you need to set up a field trip or other event at least once every two months (or some other time frame).
Other ways to advertise are through other Homeschool Yahoo Groups for your area (like for your state, mentioning you are looking for homeschoolers in your general area), and on websites such as A to Z home's cool and Homeschool.com. Good luck!
