A $100 purchase can cost more than $100 depending on how you choose to pay for it. Credit card interest, checkout surcharges, overdrafts, installment-plan fees, currency conversion, and instant-transfer charges can all increase the final cost after the shopper has mentally committed to buying. Some appear in small print at checkout, while others do not show up until a statement or account notification arrives days later. Knowing where those extra costs hide can make choosing a payment method almost as important as choosing the product itself.
