Beautiful! Those are some of the finest rifles ever made by anyone, period. The great Finnish rifle makers we know so well today cut their teeth making Mosins to save their country. There aren't many of them compared with the millions of Soviet and Russian Mosins, but due to buyer ignorance their prices are deflated right now. That's already coming to an end as more and more people learn about these rifles. Even now it's getting tough to find the pre-war Finns at bargain prices. But the prices are still quite low for the M39's and M30's--particularly since a lot of sellers don't know the difference between an M30 Finn and a Soviet 91/30.
--Look for the [SA] stamp, which is the Finnish army property stamp
--Watch for two-piece stocks joined together in the middle. The Finns used a lot of small pieces of birch.
--Look for modified front sights or "stacked" front sights.
--Look for dark colored woods. These can be black walnut on US made Mosins (worth a chunk of change if intact), or Finnish stained stocks
--Look for unusual designs in the bin that don't look like the standard 91/30 or M44.
--Look for M44's with striking blond stocks (Poles)
--Look for barrel shanks with the Tikka, Sako, and other stamps on them.
--Look for non-bubba'ed Mosins.
--Take care with the "snipers," the real ones are very rare and 95% or more on the market are reproductions.
As far as Soviet rifles, the best ones I've had were AZTEC imported 91/30's, mostly pre-war hex receiver. That outfit, which I believe has shut down, imported a batch that was above the usual quality level.
Also there are some fantastic web resources on Mosin nagant.net and 7.62x54R.net Google around.