Considering the saving on the flights, you might think about doing some shopping before your cruise for some European fashions, or FedEx clothing or baggage to your pre cruise hotel.
I know we have been looking at flights to Barcelona, and with some of the economy options, it would be less to freight clothing ahead of time, than check a bag. Especially with some of the weirdness across a new airline for each leg of our trip.
we paid about $300 more each for tickets to avoid that headache. Not sure the budget airlines really save you anything unless you can do it all by carryon. And for a cruise that is ill advised