Ouch, still so expensive. The powestrip is a good idea, not one for 5 games though, but for two as I want to be able to power the games per pair.
And I found this useful table on KLOV, which tells me that in my case 150W converters will do.
http://forums.arcade-museum.com/showthread.php?t=149845It lists 5 of the 7 games for which I need a converter, all around 110W.
So, it seems that I have two options, buy the much cheaper 150W converters or buy the 300W and connect two games on them.

@Muerto, 1000W is overkill, for the reason that I want max two games per outlet.
@Luigi, thanks for the link, could be usefull.