I agree with sourdough, I didn't even buy a starter just made one from unbleached white flour and water, it been going strong or more than 15 years now. Other home fermentation projects too, many don't really involve any special equipment. But the secret people don't realize about sourdough is its EASIER to work with, than commercial yeast. Less fussy, less sticky, more robust, just slower. And slower is easier.
Gardening there was some cost involved for me but I have been consistently shocked because I used to kill plants but the food garden is doing great. Not idyllic, sometimes bugs eat all of something, or birds do, or this year my dogs are the late season watermelon (bitches!) but in general it doesn't take a lot of knowledge, I look for sturdy heat tolerant hybrids or plants native to hot wet places, and have gotten fennel, broccoli, cauliflower, tomatoes, okra, collard greens, mustard greens, jalapenos, different lettuces, a few other veggies and the watermelon all this food for not much cost beyond what we are already paying to have a house with a backyard.