Just FYI, I had a BUNCH of old bills - some dating back to the 1800s, and I sold them on an auction site... I barely got face value for them - and I think I probably lost money after transaction and shipping costs). One lot I was trying to sell was a lot of 25 five-hundred yen notes. I started the auction at less than face value, and I still couldn't get any buyers. I ended up taking to the bank and exchanging them for full value.
There were just too many of these in circulation, and everyone who owns one has access to ebay and yahoo, etc... so it is tough to get much more than face value for these.
(If the printing number is all the same number - all zeros, for example - you can get a good price for them, but garden variety notes don't get good prices).
Anyway, that was my experience. Hopefully you'll have better luck than I did.