At Conrad Electronics I found an 5V EL inverter in a through hole package: WE-50
The disadvantage is that the inverter makes a buzzing sound that is just too loud.
Now, I wonder: Is a similar component available at Digi-Key, preferrably silent?
I read that one can open inverters and glue the capacitors to avoid audible vibrations. However, in this case, the package cannot be opened, at least not in an easy way.