Sounds like you might be confusing observed serial numbers with actual production.
Most all collector groups use this method to better determine total production numbers for guns that no longer have the maker's data to work with.
They logically assume that since 3526 has been observed, it stands to reason that numbers 1 thru 3525 were made also.
Same goes for the high number observed. If highest is say 'N' block, then prefix blocks 'A' thru 'M' were probably made as well.
Of course no 'J' block for Mauser.
The huge quantity of RCs that entered this Country have greatly expanded knowledge on 98s as well as other German made guns.
In all honesty, most collectors I know, including myself, would not feel any one 4 digit serial (with or without the letter prefix) is more valuable than another.
Condition, condition, and condition are the driving forces on most all collectible firearms types values.
Some do like to collect the much more uncommon single and double digit guns.
That looks to be a nice looking rifle and I look forward to more detailed photos.