Mercado 28 vendors set prices expecting negotiation but there's proper etiquette for tourists who aren't jerks about it. Start at 60% of asking price, settle around 70-80%. Speak basic Spanish ('¿Cuánto cuesta?' goes further than pointing), and remember these families depend on sales to survive.

Walk away politely if no agreement - they'll often call you back with better offers. Never photograph vendors or merchandise without asking first. Basic respect and saying 'gracias' gets better prices than aggressive American bargaining tactics.