Moriya Shrine | Source for all things Touhou

I don't remember if Comiket has ever been free to admission for general participants as Comiket catalog is the ticket.
A funny thing is that today there is a "probably a world first doujinshi sales event at a pro wrestling venue, and the location is Shirahama Beach" (general participation is not free) by NightSnailsCafe.

They also organize doujin events in mountains (general admission is free).
There are also other events like this. For example Flyingtown organizes events in shopping malls. They also organized an outdoor event.

There are small Yuru Camp only events which combine doujin activities and camping. And there are a lot of other events like this.
From this side there are many different doujin events. There are events indoor and outdoor events in public areas. Touhou Doujin is not exception. There were even Touhou-only events in trains (tickets were expensive, because, well, you also had to pay fares).

There were some Touhou-only events which have no admission for general participants. There were also some early events with free admission for circles, but nowadays such things are rare (at least there are no recent Touhou-only event with free admission for circles).