Some good ideas here. Thanks.
We have an older girl, so everything is a bit slanted her way. We have about 8000 princess dresses and Disney outfits, hundreds of fairys, tutus, wings, wands, a few national costumes - a chinese dress, an abeya.
Ds has an Iggle Piggle outfit, a (pink, sparkly) catsuit that is missing a tail and a fish mask. And that's about it!
Somehow a stretchy Spidey costume just doesn't seem as exciting as a hooped crinoline with jewels and pearls and froufrou frills. And he doesn't know who Ben 10 is (yet).
I was thinking of making a little caveman fur for him.
Will also investigate chef and knight and other suggestions on the thread. Pirate is a good one.