Have you ever been to a flea market? It's a market where private individuals can sell their used goods: clothes, for example, as well as books, household items, toys and sometimes old furniture – all for an affordable price that can usually be negotiated. You can take your time looking at interesting things and meeting nice people. Lots of people like buying secondhand clothes because they are cheaper and they can find unusual items.
Flea markets selling pre-worn children's clothes are especially popular because children grow out of their clothes so fast. What's more, there are usually toys for sale as well. Flea markets are sometimes part of street or neighborhood parties and usually happen on the weekends.
By the way, you can also find used clothes in secondhand shops.