from what I understand there are very few original snipers, most were stripped of their optics when they went back ot arsenal after the war, then were retro-fitted with either original or repro optics to be sold for a hefty premium nowadays. Just the usual stuff I would imagine: strong rifling, tight action etc. But I'll let the experts answer that one *cough* artyman *cough*
*edit* I think westrifle has the lowest price of $630 with what I would geuss would be his repro scope and mount made on the original tooling in Mother Russia, with Love
Thanks for the mention

but I am far from an expert, especially seeing as how I dont own a legit sniper! (yet...

)
You are correct in that after the war many PU/PE/PEM snipers were "decommissioned" of sorts out of their sniper roles and were converted back to infantry rifles prior to storage after refurb. Many theories exist as to why this was, many speculating the cost prohibitiveness of upkeep on scopes. I have no idea as to how valid this theory is (how much could it cost to keep glass?), however this seems to be the most widely spread theory. Personally I dont see how taking a bunch of scopes off already assembled rifles makes sense but I wasnt there

. I have also heard that the "ex snipers" are now "ex" due to them being too worn out to achieve sniper standards. From what Ive seen this doesnt hold much weight as I have seen some ex sniper rifles shoot very, very accurately. Much more accurate then the standard of the day. So all in all, a bit of a mystery.
In regards to the repros we see currently being offered by our dealers, there are a bit of variations. Most of the repro PU rifles are not ex snipers, rather standard infantry rifles that have been assembled in PU configuration semi recently. These rifles typically shoot very, very well and are very functionable firearms.
There are also ex snipers that have been "re converted" in a way. It was/is also common for people to buy ex snipers (such as the ones mentioned above) and "re sniper" them. Repro/modern PU scopes and mounts are added aswell as a bent bolt handle. I have heard it is a very painstaking process to do this as the original holes that have been filled in are very tough to re drill. I have heard many stories of people buggering this all up and are now left with a Mosin with holes going every which way

! It can be done however and by some is seen as more authentic.... depends on your views. It still is what it is, a 91/30 with a modern PU and mount. Trying to pass off as a real, legit WWII sniper (which it is) with a correct scope/mount (which it isnt) would be dishonest in my opinion.
I do not have an ex sniper in my collection however they are not rare by any means, and can usually be had for 250-275$ cdn. I can see myself grabbing one eventually. Sorry for the long winded post!