How much does it cost?
'Costa' — COS-ta. Stress on the first syllable.
The most essential shopping phrase in Italian. Use it for any item — food at a market, clothing in a boutique, a ticket at a museum. Short, universal, and universally understood.
'Quanto' = how much. 'Costa' = it costs (third-person singular of 'costare'). No subject pronoun needed — the context is clear. For multiple items: 'quanto costano?' (how much do they cost?).
Quanto viene?
How much is it?
'Venire' used colloquially for price — very natural in shops.
Qual è il prezzo?
What is the price?
More formal — asks for the price specifically.
Quanto costano tutti e due?
How much do both of them cost?
For two items together.
In Italy, prices in shops are legally required to be displayed. However, at street markets ('mercati') and flea markets ('mercatini'), prices are often not shown — asking 'quanto costa?' is the start of a negotiation there.