I paid $425 for a very nice (VERY) 03A3 late last year.
It is a 4 groove barrel, and looked like it had not been fired more than a few times. It has a C stock that was pretty clean and properly marked. It is not really a collectible as it is a '43 and probably had a few parts on it that might or might not be from the original date of manufacture.
It shoots great and has become my favorite rifle to shoot. What a shoulder thumper.
If it is an 04 and clean, I'd say it is worth the price.
Go over to the Gun and Knife
www.gunandknife.com forum and log onto the 03 forum and ask those guys. They know every darn detail of every collectible martial firearm the US issued. If you can gather some numbers, someone over there is sure to be able to fill you in on the skinny.
EDIT: gun and knife appears to have folded. Sorry. It was a busy and well informed forum, but always had troubles. Try this instead:
www.jouster.com/index.htmlRay