Most of the M-1 Garands will be of Springfield manufacture, but you may get lucky with a Winchester or International Harvester. Of course WWII vintage Garands are the most sought after
When it comes to the M-1 Carbine, there were many more manufacturers, ten war time producers with Rock-Ola Juke box company versions being the rarest, there were also paratrooper models with folding stocks (designed to fit in a thigh mounted holster)
There are other WWII vintage guns available, you can easily find the Soviet Rifle known as the 91/30 Mosin-Nagant. These are available in arsenal refinished condition and are great shooters. If you are lucky you might find a battle worn one that has not been "re-arsenaled".
The best part is you can find them for $100-$150. Again War time built guns are more desirable as are the older hex receiver guns
It is getting difficult to find an original, unmolested one as many were sporterized during the 50's & 60's.
Speaking of Walther pistols, these are also in plentiful supply, good luck in finding a WWII vintage with the Nazi proofmarks, but they are out there. Most of the P-38 and P-1 pistols available are post war versions with aluminum frames, which spent time as police duty weapons in Europe.
China also makes them (in 9mm as well as the 7.62 x 25mm) Ammo was once plentiful, but has since dried up somewhat. There are some commercial rounds available, but the price is a little on the steep side.
The Russian 1895 Nagant pistol is also easy to come by, not all that much fun to shoot, but they are cheap and very unique.
More guns from Eastern Europe include the CZ guns, both the CZ 50 & CZ 52 can be found from importers for reasonable prices
Be careful what ammo you use as these do not shoot the standard 9mm Luger (9x19mm) round, they use the Russian 9x18mm, some of the new ones can be had in .380 ACP as well (9x17mm).
Another surplus gun that you can get from the "Mother land" is the Simonov Karbine, also known as the SKS. The Russian, North Korean and North Vietnamese ones are the most desirable, but the Yugoslavian and Albanian are also very popular with collectors. Starting in the 1990's the U.S market was flooded with Chinese made SKSs, some of which were built on Soviet tooling and were of really good quality.
Used Glock 17s and Beretta 92s are out there, many times the guns were carried a lot, but shot very little.
There are many others out there, the PPS, & PPSH, Suomis, FEGs, etc.. If you are interested in getting a surplus gun, pick up a copy of the Shotgun news sometime.