So, Thomas got to wear his costume to dance class today - I did end up having to put ties on the front of his vest (black ribbon)- in part because he kept trying to take it off at first. He put on his pirate shirt and pants without complaint. Getting the vest and sash on him was a totally different story - but eventually he was okay with it - esp. as Grandma came and made a fuss about him and then we took him to see a neighbor to hype it up a little and he got to run around in the dusting of SNOW we got last night. 
His pants are just the green cut-off sweats he usually wears to dance - I sewed on a patch (out of the same pirate fabric as his shirt) to cover up the Old Navy logo - and then added one to the knee, too.
The sash is a piece of old pillowcase from the stash Eva gave me. I was going to put another piece on his head like a bandanna, but gave up - this is one pirate that won't wear a hat or a bandanna. I'm just happy he wore what he did.
And of course, those are his sister's socks - but they really make the outfit, yes? Total cost of costume = $2.
I was kind of surprised anyone took more than a glance at his costume - I'm happy with the way it turned out, but it is still just a thrown-together costume - but all the moms and his teacher really liked it. They all asked if I made it..... "Well, kind of."