Bring plenty of small change
At most flea markets, many sellers are individuals, and giving change is part of their work. A large note takes time to break, especially early in the morning. So shoppers who arrive early with small bills and coins are often welcomed.
A good idea is to bring a few 1,000-yen notes, a few 500-yen coins and plenty of 100-yen coins. Even if your wallet fills up with coins, you will not be caught out at the moment of paying. Keep money for the trip home as well.
Card payment depends on each vendor
Many vendors accept only cash. Whether cards or e-money are accepted is decided by each vendor, not by the venue. Ask before you buy, or plan on cash as the main way to pay.
Items that are not sold
Each venue has rules about what vendors may sell. Food, live animals and dangerous items are commonly banned, but the exact list differs from venue to venue. If you are looking for something specific, check the organizer’s notice rather than assuming.