Get everything you like and can afford. Look around and know what is what and you can find some really great Milsurp firearms for not that much.
It's almost a crime, not to stock up on cheap and like new Moison Nagants
Same with K-31's. Actually, I haven't bought one yet, Instead, I happened to find what I believe is a Swiss 1896/11 Alpine Sporter, the Alpine sporter part being a marketing gimmick, that thankfully, only involved the cutting back of the forestock. 1911's, the rifle that is are also nice but cost up yto twice a K-31 price.
Swedish Mausers are great, but so is an AG-42, a semiautomatic rifle that replaced it. I found one for about half what they are worth, and the rifle is quite fun to fire, although it tends to eat brass. About half are trashed.
German Mausers are also quite good. A K-98 is essential, but how about it's WWI predecessor, the GEW 98? The German made Mausers, that were exported to several South American countries are quite nice. Personally, I think the 7MM rifles are a bit preferable to other calibers.
Yugo and Czech Mausers are great rifles, though probably not quite as historical as other Mausers.
There are tons of Enfields out there in several models, including the Ishapore models in 308. I'm not into them personally, but many people are and recommend them. And 303 can still be had in surplus.
FN-49's are great. I passed up on a really nice Venuzualen some years ago in 7mm and I've been kicking myself since, especially since I can now find surplus 7mm. Instead, I got a Argentine navy model in 308 with removable magazines. The regular magazines are removable, but these are actually designed to be removable. The rifle also comes in 30-06, but it seems the most common is the Egyptian 8mm.
While you're at it, grap an FAL replica.
You need a Garand.
The PSL is an actual Romanian military rifle, and not a replica, although I am reasonably sure, the parts are being made new specifically for the US market.
All SKS's, except for certain Chinese models are surplus. Russians are usually really nice.
AK's? Replicas, but get some anyway.
Lugars? P-38's? Cool! Available. To be really cool, get a German Broomhandle Mauser. Some of the Webly's are also cool, as are the Moison revolvers. The DA version is also very cool.
Grap a Tokarev pistol, and a Tokarev rifle. And get a CZ 52. And a Makarov pistol. I got a RUssian made one, it's not really Milsurp, but it is a really nice DA auto.
If price is no object, and neither is ergonomics. Get a DP-28, a Semiauto BAR, Browning 1919a-2, an MG-42 semiauto, ect. I am trying also not to be envious for the guy that posted the G-43's, because Envy is a sin, but I would really like to have one. I got my SVT-40 for a decent price, but for the longest time I believed I wouldn't be able to find one, so who knows? Maybe I'll find a G-43 for a decent price. Oh yes, don't forget the Johnson 1941. Someone specializes in redoing them, but they are several thousand dollars.
1903's are alright, and think about a Steyr M-95, the "other white meat", I mean the "other straight pull rifle".
Japanese type 99 are good and strong, and ammunition is difficult, but not impossible to find. I missed out on ohe that had the bayonet and the AA sights. It might have also had the monopod, but the bayonet was skrinkwrapped to the stock and so massive I could't see if the monpod was there. I also missed out on my grandfather's trapdoor Springfield. Krags are also nice, but like Enfields, I'm just not into them.
Well. that's about everything.