It’s the same in that most fruits and vegetables you can buy at the store have been bred for quantity and shipping. Home gardeners can grow varieties that are bred for flavor. So my Nebraska Wedding Tomatoes may not survive a trip across the country with UPS, but they taste amazing. And my Double Gold raspberries don’t produce bushels, but they’re the best I’ve ever eaten. I do think I’m probably saving money growing garlic. Very low maintenance plant, and I grow enough to save what I need to plant for the next year. So some crops are pretty cost effective, but some are really for the flavor.
You can! You just need a vinegar mother! I’ve not done it myself, but the way I understand it you can transfer the mother once the vinegar is to your liking, then on to the next one.