And as far as buying on line, yes you are buying a "pig in the poke," but generally for LESS than the going retail rate. While I have bought some GREAT rifles on line, I have also bought some not-so-great ones as well, but I have NEVER sold one of the "non-keepers" without making a profit, usually the difference between what I paid and the going retail rate at least, so there is not the risk you think there is.
Of course, I have my CRFFL, and usually "pick up" from SOG or AIM to save shipping, so you would have to also figure in the transfer FFL fee, besides the shipping to be sure you are getting the good deal.
But I too have bought some of my collection from stores and gunshops, WITHOUT using my CRFFL. For example my M38 cavalry carbine is the last of about 12 I owned, all in great shape but the only one I found that shot as well as my M44s, and it was from a gun shop! I would buy one, shoot it, sell it for more than I paid for it, buy another, etc, until the one I found that shot well I probably had NOTHING in it considering the $10-$20 profit I made on each of the others that looked FINE, but shot 8-10" groups at BEST at 100 yds
The one I finally kept will do about 2-3" like my M44s, from a rest.
My Yugo SKS 59/66 was on sale at Dunhams for $99, when my CRFFL wholesale price was $99 too! The tax I paid was the extra I paid for the ability to pick the best of 3 they had in stock.
My Yugo M57, and my CZ-82 I also bought on sale at a gunshop, for a little more than I could have gotten with my CRFFL, but again, I got to pick the "best of the litter," not what SOG or AIM gave me....