I have seen excellent used condition ones selling for between $450-$600 and used ones with scuffing and signs of a lot of use selling for $300-$400 on ebay and selling.
There are several variations of the 657 mountain gun. these are indicated by a dash (-) and a number after the model #. The general rule is the lower the number after the dash the earlier the manufacturing date and the more valuable the gun. unfortunately it is not that easy. There many other factors that determine value and each gun needs to be appraised individually. To be very general, Model 657's values range from $500 to $1000. Mountain guns usually bring a premium.
5 is in tens place
The digit 6 is in the hundreds place value in the number 657.
50-600 usd
500-600 USD
1, 3, 9, 73, 219, 657
657 is a composite number.
9907 + 657 = 10564
997
65789+657=66446.
-100
989 + 657 = 1646