LATAM has round-trip flights from New York (JFK) to Montevideo (MVD) for $490 with a connection. Flights September to November. Very few weekends available.
Note: Vayama has this for $470. If you plan on booking there, be aware that they charge $100 to cancel or change a ticket. Travelocity will allow you to change or cancel the ticket without a fee within the 24-hours after purchase.