Hi everybody!

Bartering is a particularly satysfying form of exchange. It increases your range of stones and that of your friends. No money is exchanged, thus lessening the immediate economic impact of broadening the type of stones you can use in magic. It is quite common among collectors who go out and dig their own, which leads us to the third method of obtaining stones.

I don't get the part in bold. I understand that they do not exchange their stones for money and .....??? Can you explain that to me, or maybe write it in a different way so that it will be clearer to me?

thank you
barter: change a stone for another stone
no money, thus no economic impact