50-200 USD or so
Could be worth up to $500 for an immaculate, all matching rifle. It replace the Mauser Model 1871, used a 7.65x53 round nosed cartridge, variants of the rifle were also adopted by Turkey and throughout most of South America.
$15 to $40 depending on condition.
Dependent on the condition, between $50 - $150, maybe more if you can really push the sale. I paid $75 for one in immaculate condition in 2004.
50-500 USD
This rifle (Mauser Model 2000) is worth $350 in excellent condition.
$450
100 or so
100-1000 usd
How much does an 1899 German made Mauser 6.5x55mm worth? Or how much would one cost to buy??
Depends on whether this is a pistol or a rifle - Mauser designed and produced many guns. Also, what condition it's in.
Mauser Waffenfabrik never manufactured a .30-06 rifle. You MIGHT have an M1917 rifle, which can be worth over $1200 in good condition and all matching serial numbers.
You really need to get it appraised by an expert. Value will vary dependent on condition, whether or not all parts are matched or not, original finish or refinish, whether or not it's been sporterised, what accessories come with it, etc.