John:
The macerated tonics you can make are about as good as your herbal knowledge is. Which is what I find makes them so much fun. The possibilities are endless and can rage from the subtle to a kick in the mouth. Its pretty amazing how many of the popular drinks in Europe ,and some in the states, are originally old school tonics.
I"d suggest getting a good book on herbalism. Sadly these days it"s not taken very seriously, so there are very few "scientifically" written comprehensive books about herbs, their essence flavor and their physical effect ,Even some of my friends studying neurosciences have to rely on detailed "alternative" texts for some of their toxicology studies,.
Also not every herb"s essence tastes or has the aroma of the herb its extracted from, that"s why many of the tonics rely on heavy, flavorful herbs for their over all aroma ,Like Anise, Fennel, Melisa, Mint, Licorice, and to mask the less pleasurable flavors of some of the other components.
Unless you have a rather huge garden, I would not recommend growing and drying your own herbs. The amounts needed are rather large ,at times almost a plant full at a time,, and considering the amount of trial and error here, this might be a rather exhausting possibility. Especially with the herbs that are harder to cultivate.
I order many of herbs from
http://www.mountainroseherbs.com/bulkherb/bulkherb.php Their quality is not top notch, but they have great prices.