Pure herbal drink costs a few pence to make at home, tbh.
Hit one of the Asian stores to get a variety of herbs for cheap.
Exactly what I do. Also, from time to time I buy a mint plant, slap it into a large pot with some decent soil and wait a bit. Keep it well-watered. It’s not long before for have a large supply of free mint for years, requiring just a few leaves and hot water to brew. Very refreshing.
Normally, after one is established, I snip a couple of cuttings, stick them in their own pots and, voila, stuff grows like weeds. It means I can alternate the harvesting, and if I lose one or two…. ;)