Yes and no. Things that don't cost money:
Attending local fighter practices Attending populace meetings or business meetings Attending guild meetings Attending virtual activities Learning from members Engaging online in SCA spaces
Things that cost money:
Purchasing a membership -- this is not required, but we do recommend it. You get a discount on weekend event fees and access to online materials. Investing in projects -- different people have different hobbies. Activities like making clothing, making armour, flameworks, calligraphy all require materials and supplies, and supplies cost money. Many local groups invest in supplies for local guilds, which new folks are welcome to use, but if you're pursuing your own interests, that could cost money. Investing in combat equipment - while SCA groups do have loaner gear that you can borrow when you're first getting started, we encourage folks to eventually acquire their own gear. It's very possible to get items for discount or for free from other SCAdians, but sometimes you'll want or need to buy your own equipment. Attending weekend events -- the major activities in the SCA are our weekend-long camping events. These events have a site fee, and sometimes a feast or camping fee. In general site fees are around $20 for the whole weekend, feast and camping varies depending on the location. The SCA has a family max that allows two adults to attend an event with minors for the cost of only the two adults. You'll need to consider travel, food, site fees, and more when you attend events. Local groups can be a BIG help for sorting out plans. Some classes -- sometimes teachers will offer classes that come with "kits" or materials that are provided to attendees. These "hands-on" classes will often have a $5-$10 fee in order to help the instructor cover the cost of materials.