Ruger speed six's are selling between $200 & $275 depending on the condition. I just repurchased for $200 a .357 speed six that I originally bought in 1983, I believe that's what I paid for it new, it's had less than 1 box of ammo fired in it but you're unlikely to find one in this condition. Gunsmiths report that they have never seen a single six that was worn out but if you need new bluing you should consider paying less.
Model numbers 117 vs 207 and external physical features
75-260 or so
100-300 USD
100-300 USD
100-400 USD
50-200 USD
200-400 USD
Impossible to value with just the serial number.
100-300 USD
200 or so
40-300 USD or so
50-200 or so