B&K is a great place to start, Brian is one of the best guys around. IDC Firearms in Clinton used to always have a rack of them. That's where I bought my first two, but it's been a few years.
If you can make it up to NH, Collectable Arms in Merrimack always has a big rack of them, and I suspect that the big shops in Hooksett would have some as well. I'd expect to pay around $150-175 for a 91/30 in a shop these days. They days of $99 Mosins in shops are gone, and the $99 Mosins on-line are limited to very infrequent sales that do not last long. I'm not even sure I've seen one of those for a while.
Getting your C&R license is a great idea. It's $30 for three years, and you will make that back on the first rifle you buy online. And chances are, you will want more than one.
As far as condition, if you are looking at them in a shop, you'll pretty much go for the one with the nicest stock. Sure, check the bore, check for counterboring, and check for matching numbers. That all helps the value, but really doesn't make much difference in how they shoot. Mine run the spectrum from mirror to dull grey, matching and non-matching, and they all shoot the same groups.
Good luck and enjoy