You can ask whatever you want. It's only worth what someone will pay for it. I did some quick research and you're pretty much bang on that combo being about $400 to find now online.
Now the question is would I pay $300 for something used (even used for one run is used... no warranty, etc.) when I could get new for $100 more? Not me, but somebody might. I'd say ask $300 and you'll probably get $250 for it if you find the right buyer.
Hope this helps...