Depends on what you want it for--pristine examples of military rifles are collector items and their very scarcity drives the price up. In most cases, these rifles have not been "new" for over 70+ years and even some of the collector items will exhibit some storage wear. The collector grade rifles are bought for their perfect appearance and shooting them will more likely decrease their value.
The shooter grade is pretty broad but a rifle with little or no original finish might just have a fine bore. A rifle that looks pretty on the outside might have a crappy bore. And some of the shooter grades will shoot patterns like a shotgun while others, despite being worn, having dark and pitted bores, might shoot good groups for military rifles (2-5 MOA) @ 100 yds is not uncommon with issued iron sights.
At the bottom end, are rifles that have severe pitting, virtually no rifling, or are converted, monkeyed with, sportered, etc.
The cheapest way to buy a good looking and shooting Enfield, if that is what you want, is to buy one of the plentiful sporterized versions. If you get one that doesn't have the barrel chopped, you always have the option later of trying to restore it. In most military rifles, barrels are no longer made, and to have a duplicate barrel made for a 6.5 Norweigian Krag has no economic sense.
You want one in military trim, keep an eye out at Century International and get your collector version of an FFL where you can buy direct. They are selling a bunch of sad looking Enfields converted to .410 but with full stocks, etc. You clean it up, you can have a presentable wall hanger. You can also get other rifles from them, time to time, now in small quantities. J&G Sales is another place to find these.
Checkpoint Charlies, Simpsons Ltd, Liberty Tree Collectors, oldguns.net, Joe Salter, and some other dealers found in the shrunken Gun Digest magazine still have collector military rifles available but you will pay the market price and perhaps a bit more with a bit more protection on provenance, etc.
Gunbroker and other auctions, and don't forget pawn shops and the like, can be a good place to get either low end parts rifles or sportered versions. Pawn shops and local gun stores either price the sportered versions cheap or they price them as if they are complete pristine military rifles which is a bit idiotic (but hey, they have a cheap commercial scope on them) so they can be hit or miss.
In sum, for a rifle that is both collectible and shootable, and a fine piece of U.S. military history, you cannot go wrong with a CMP Garand. Ammo is and will be available as are spare parts. They have different grades and if you want a pristine one with excellent provenance, they have them or if you want a service grade, they have them.
Don't buy a collector grade and hack it up to make an inferior sporter. Best to sell it and then get a new commercial rifle that will be more accurate, have spare parts, and usually be in cartridges that you want to shoot. Taking a T38 Arisaka in full battle dress to make it a chopped barrel bambi blaster in 6.5 Creedmoor is a fools errand.