Realized I typed prefix when I meant suffix as I believe none were made with a prefix.
Your pictures lack the definition (lighting) for me to really judge the originality of the finish.
Really tight settings on your camera with bright lighting or natural light will help bear that out with photos of the proofs.
I'll hasten to add that what I can see looks straight.
Also, look for a number on the cleaning rod. It should match as well.
How about a shot of the butt markings and a couple of over-all shots.
Your best way to evaluate sales trends would be to track auctions of matching 98s to their completion, and I don't mean wasting your time following reserve ones.
Search k98, 98k, and k98k.
If you are looking to find a value, it will be a little longer search.
Millions of 98s were made, but the rate of attrition on the guns grows exponentially as you go back towards the early years.
What I mean is that it is much harder to find a 35 or 36 in the same condition as a 44 or 45.
The majority of the early rifles went with the two million Germans into Russia in 1941.
I would think the value to be at least 50%, if not more, than a 43 or 44 in similar condition.