A basic sporter 03 by a good gunsmith copying the work of Sedgely, Pachmayr, G&H, etc is going to go for $325 to 400.00.
The real ones go from $700 to whatever.
I bought a journeyman 03 sporter from an old smith who had converted at least 1,000 Mausers and 1903s, for $300.00.
This summer, I looked at a Griffin & Howe 1903 in .400 Whelen that was not much nicer, but $4,000+.
All you can do is spend what it is worth to you.
There is no such thing as an objective price on something that is not a commodity and you don't plan to resell.
Example: Al Linden
http://www.drake.net/html/vintage6.html