Some stores give discounts for paying cash (although check before you get to the till); others charge a premium for using credit cards. Carry both, and keep your options open. Tourist-area shops may try to charge you in dollars or euros what they charge Argentineans in pesos. Always confirm which currency you're dealing with. Bargaining is accepted only in some leather-goods shops on Calle Florida. Elsewhere—even in markets—prices are fixed, although it is worth asking for a small discount if you’re buying several of the same item.
"Refund" is a dirty word. No shop will give you back your money just because you change your mind. Even if a product is faulty, exchanges or credit notes are the norm. Many shops won't process exchanges on Saturday, a busy shopping day.
Keep receipts: the 21% V.A.T. tax, included in the sale price, is refundable for purchases over 70 pesos at stores displaying the Global Blue tax-refund sign. Visit the return desk at the airport to obtain your refund, but remember to have the goods on you in order to present them to officials.