Today, when you want to acquire something that you don't make yourself, you buy it with money. How did people acquire things in the pre-Roman Celtic world?
Let's say you wanted to acquire something expensive, like a chariot. Would you gather up enough things to trade for it? Would someone simply give you a chariot and you'd be expected to give gifts in return?
I'm aware that currency showed up at once point, but I'm particularly trying to learn about non-currency methods of buying things.