Like any other hobby, it can be taken to extremes. Like no other hobby, gardening is actually MORE productive when the cheapest and free materials are used in the pursuit. Of course, the gardener has the advantage to pursue a leisure activity where most of the rules and supplies have already pretty much been defined by Mother Nature and she didn't have a whole lot of capital to work with. No need for fancy nurseries. Seeds can easily be pulled off any existing plant and saved o'er the winter for the next summer's gardens.
Plants lend themselves quite well to propagation and there is a plethora of books to explain.
Established gardeners will all but jump over the fence at any request for a cutting to so offer. Indeed, many perennial plants demand that they be pulled from the ground, split at the roots and re- planted as separate, now multiple, plantings. Well since most of us already pay some sort of rent or mortgage there is no additional charge to actually plant something in the earth of the surround. But the plants do perform better in a plot of land that most suits their needs. Fortunately for the gardener's pocketbook, such soil amendments are absolutely free and use only that which we throw out anyway.