I vote thrift store as well. Ask around with your cosplay friends or just stick around here on the forums and you're sure to find someone who can help or take a commission for the hat.
The wig, you could find online and trim or dye to your specifics [that's a very pretty lavender]. I'm so thrilled that you're going to cosplay from Un-Go
I'd recommend liquid liner and have fun with mascara, for the eye makeup, but I can post pics later with details. ^^ Have fun putting it together!