A site that specializes in JDM parts probably. Often if they can get some things for you (say some similar products for example) then they might be able to source this for you too. Don't expect it to be cheap though.
Oh, and I'd expect it to have some of the same problems I've heard US Integra cup holders have. I know a few Hondas have these kinds of cup holders and I'm pretty sure my sister's Integra did too.