Determine what you want out of them first--do you want potential price appreciation, are you going to shoot them, do you want to use them for other applications such as hunting, firing in milsurp matches, reloading for accuracy on that rifle, etc. or do you want historical value?
Price appreciation depends on condition and rarity--ideal are unissued condition and/or rifles with historical importance and proven documention. I saw where a M1 Garand that had been accurized for Sen. JFK just went at an auction for over 130,000 but letters, condition, etc. were perfect. Would not be surprised if that price doubled in twenty years for that rifle. But, why would you shoot the darn thing and what kind of security level are you going to spend to keep it. And, depending on the economy and changing collecting tastes, expect large fluctuations in value. That would keep me up at night and I prefer more liquid assets.
If you want to shoot them, then price appreciation exists but it will be more modest depending on condition. But, you will be out much less and be able to have fun with it. Be that as it may, what value they have will be reduced if you later want to sporterize it, tap the receiver to add scopes and bases, etc. But, in obscure calibers, you will be forced to reload if you shoot it very much and brass/bullets/reloading equipment will cost more. Conversion to another caliber damages what value is left in a shooter grade and is costly in some rifles.
Competitors usually want to optimize a few rifles and fire substantial amounts of ammo which often means new barrels, match ammo, etc. while historians might value something that was a relic which can never safely shoot again. Thus, your personal needs and wants should dictate what you should buy.
My personal path is probably not yours, etc. but I started with a WWII vintage Mk. 4, no. 1 Enfield that had been lightly sporterized by chopping the stock and removing the handguards. I decided to restore it to as issued condition but had to find out exactly what that was--thus I learned a lot about the development of the rifle, history of manufacturing, and then added reloading rifle calibers when I could not find ammo for it.
Already had some talent and tools for woodworking and mechanical ability so I learned a lot more about stocks, diagnosing mechanical problems such as feeding, accurizing, and so on. Started reading gunsmith manuals, hanging around in forums like this, reading up on the experts in their fields, and so on.
Since then, I have restored and rebuilt several dozen milsurps with a few bought that did not need anything but a good cleaning. I do it primarily as a hobby and because I value the craftsmanship, history, and mechanical genius that these rifles reflect. To me, it means a lot to have cartouches appear on a battered and dirty old stock and see old arsenal repairs. Rebuilding something that might be destroyed also appeals where I have rebuilt broken stocks.
I also reload for these calibers in order to use them and to wring out as much accuracy from them as I can and enjoy the process to find the right recipe for accuracy in that rifle.
If I sold every one of them today, it would probably be about what I paid to restore them over the last ten years, maybe make a small profit, and maybe double it if I took the time to part them out. Counting my time, it is certainly not an optimum investment but it has helped me through some challenging medical issues where I could do little but work seated at something. That was worth it for me.
Thus, answer the questions for yourself about what you want and then what you should get should answer itself.
