With British Airways flying out from Copenhagen to Los Angeles and back from Las Vegas to Dusseldorf for only €373. Bookable on the german version of Ebookers. You should search a multi city flights. Just click on ‘Mehrere Stopps’ in the search form.
Outbound: Copenhagen – Los Angeles (6 November)
Inbound: Las Vegas – Dusseldorf (18 November)
There is a stopover in London on both ways and there is one more in Charlotte or in Philadelphia during returning back to Europe.
Just click on the image below to check it:
Budapest – Malmö, Wizzair (5 November), €13. Bookable on Wego.com.
For your information: On the way back to Europe there is a stopover in London, where you can simply skip the last leg to Dusseldorf and get off the plane if you want and take an another flight from London to your home. However you have to add Dusseldorf as a final destination because this is the only way to reproduce this fare! It is not possible to skip the first leg Copenhagen – London, your ticket would be cancel then.
London – Budapest, Ryanair, (19 November), €19. Bookable on Wego.com.
Ryanair flights depart from London Stansted Airport not from Heathrow. You can get to Stansted Airport from London city center with Easybus for only £2.
From Los Angeles to Las Vegas you can take Megabus. They usually offer seats for only $1 on their routes.