The M91/30 Mosin Nagant is a well made reliable rifle capable of excellent accuracy. I have collected them for many (many Yikes!) years. My main interest is the Finnish variants, as they are rarer and improved Russian/Soviet models.
I would suggest, if you haven't already been there, to look at
http://7.62x54r.net/ and
http://www.mosinnagant.net/default.asp . They are both excellent on line sources of information on these rifles and their history.
The rifles available from Trade Ex and Ellwood Epps (sourced from Trade Ex and IZH) are excellent condition refurbished models. Some are original all stamped matching, some are forced stamped matching, some are electro pencil matching. Often, the parts are a mishmash of both Tula and Izhevsk components.
Like all surplus firearms, barrel condition varies greatly, from as new to uniformly pitted. Some have been counter-bored to improve accuracy due to a worn crown or muzzle (cleaned with a steel rod from the muzzle end as per service regs).
Rifles made between 1942 and 1944 often have very crudely finished receivers (lots of tool marks, etc.) due to wartime production cutbacks. They are just as safe, but not as pretty.
I would suggest you determine what exactly you intend on doing with it (collectible, casual plinker, target), view the above websites, then determine what specifics you want in your rifle. You can then request the dealer locate one that meets your requirements. I have bought from both sources, and am always satisfied with what I receive.