A few hundred to a thousand depending on condition and if the barrel is in fact 8" and came from the factory that way. Only way to know is to get it lettered.
$750.00
6500
about $500 New in box.
100-500 USD
the value of a smith Wesson 8 inch barrel model 27-2
100-400 USD
100-300 USD
100-300 USD
50-550 usd
50-550 usd
50-500 uSD
Your smith and Wesson model 686 is valued at 250-425 dollars depending on condition.