Looking to Exchange Cambodian Riel in Bangkok - Any Takers?

I'm in Bangkok now and have a bunch of Cambodian Riel thinking I could exchange it for baht later on, not realizing that it's only accepted in Cambodia so I can't exchange it anywhere. I'm wondering if there's anyone travelling to Cambodia soon that would be interested in it. I think I have 400,000 riel (~100 USD, or 3200 thb) and my girlfriend probably has a similar amount if not more. I'm not looking to give it away, but I would give a generous exchange rate on it to make it worthwhile.