Duncan Phyfe

I have this China cabinet wich I believe to be a Duncan Phyfe style cabinet. I want to sell it and before I do I'd like a better idea of what it's worth. I paid $200 for it 8 years ago from an old woman. I can't seem to find enough online to figure out if it's an authentic Duncan Phyfe or not, I know the likley hood is very slim but I'd like to at least figure out a time period.

The back side is a real wood panel that is 1/8th inch thick, not that crappy pressed board stuff. It's attached with rounded 1/2 inch, flat head screws. The only identifying mark I can find on the entire cabinet is on the back panel in black lettering "1620 CHINA"