How much are the black A100s going for these days? I found one for 500 but I don't want to overpay.

I'm wanting something that has oem looks like the denon or nak, but some decent sq. Its going in a miata, so I don't want anything flashy to attract attention. I'm using a metal black mount that I can ISO flush mount the unit. So a black Denon DCT series unit seems like it would be perfect.

Anybody have a good resource on the hierarchy of the dct series on lowest to highest quality and the differences?