The top one, the Saiga, is a Russian attempt to "sporterize" the Kalashnikov (AK) system. They aren't worth very much, if that example can take the double-stack magazines (I don't think it can because double stack guns tend to have dimples in the reciever on either side of the magazine well) its worth $250-350, if its a single stack magazine then its worth on Par with a garden variety SKS, $150-200.
The SKS is actually the most valuable gun out of that lot, as Chinese SKS's were only imported and popular for a few years before firearm imporatation from China was outlawed via an Executive Order that Clinton signed. There should be some importation markings on the barrel left by the company that imported it. Assuming that it was one of the early ones (good probablity since its Chinese) then its legal to have the folding stock on it, and because of this it'd be worth $250-400 depending on what all you also had for it. Ironically, my Dad has an original Norinco Chinese SKS with the exact same folding stock on it, only my Dad also added a spike Bayonet and the 20 round fixed chinese magazine.
Edit: outofstep makes a good point that some cities/states still have laws prohibiting folding stocks and the like despite the sunset of the 1994 crime bill. Note that your gun is still subject to the earlier 1989 "bush bill" that started the whole thumbhole-stock craze because it banned import of rifles with pistol grips. That stock is technically illegal on a pre'89 SKS. You can probably check the serial number range (all but the last three digits or so) with the importer who should have stamped their name on the barrel somewhere so you can check when the gun came into the country, and if it was subject to the '89 bush ban.
The "mauser" isn't a mauser at all, That is an M1944 Mosin-Nagant (pronounced Mozeen-Nah-gone) Carbine. Its identifiable as an M1944 (aka M44) because of the fixed side-folding bayonet, earlier carbines were made from original full-length M1891/30's and cut down to carbine length and called the M1938. Your M44 should be marked as such as it was made in carbine length and as such it will shoot a lot better than most M1938's.
I have an M1938 that I paid $80 for at a gun show, Russian M44's in good shape can be found on gun store racks for $100-150. For the money those guns are more fun than I can possibly explain, the short barrel and the full-house rifle cartridge (which uses slower burning powder to take advantage of the longer M1891/30's barrel) results in a spectacular muzzle flash and blast that will clear out the lanes next to you at almost any shooting range. Typically I'll refer to it as my "Noisy Maggot" instead of Mosin-Nagant.
Here's a pic of me firing my M1938 a few months ago:
