ITA, Delta, British Airways, Iberia and various other airlines have round-trip flights from Los Angeles (LAX) to Milan (LIN/MXP) for $492-$519 with a connection. Flights January, February, March, April, October, and November. No Friday departures. Extended weekends available. No Thanksgiving dates.
Some small OTAs on Skyscanner have this for as low as $458 when flying on ITA; a price that is is cheaper than the airline. If you plan on booking there, beware of any site that charges a fee to cancel a ticket within the 24-hour “free” period. Use unknown booking sites at your own risk.
A Carry-on bag and also a personal item is allowed for free on Delta. You can avoid paying for seat selection by accepting the randomly assigned seat at the gate.