Be careful on that price quote.
His quote would be for rifles in close to excellent condition.
Right now, it seems that milsurp prices are down from before Covid prices.
Much of that is due to the present state of the economy, fear of new prohibitions and a severe lack of reloading components, huge price increases on ammunition and even availability of factory ammunition for those rifles.
The folks that were passionate about collecting them are getting older and the younger folks are more interested in "black plastic"
From the condition of the rifles in the pics, one is well used, so if the bore is in EXC condition, $575 would be top end.
The other rifle appears to be unissued, after an FTR and it might easily bring $700-$800
Condition is everything when it comes to "collectables" and top prices are only paid for the best.
To my knowledge there is very little, if any surplus 8x57 ammunition available. Yugoslavia provides the best venue to purchase commercial ammunition but it's not cheap.
Most people like to shoot these rifles and many of them were purchased as shooters, to save the German variants.
Great rifles and well built.