I haven't commissioned from them before - however, since it's too late to let paypal do anything, try going to your bank or phone your credit/debit card company and specify that you want your money back.
However, if you know of any other sites that they may be active on, it's worth checking them out and sending them messages there. Or try and trace up close friends of theirs.
Sorry I can't be of much help. Good luck.
Sera Myu Eternal Sailor Moon - Sera Myu Musicals - 95%
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Sailor Cosmos - Sailor Moon Sailor Stars
Bubbles - Powerpuff Girls Z