A 2 1/2" M586 is a $1000 gun (give or take), if in NIB or ANIB condition.
These are scarce. There were two different models made, one in 357 mag and some export models chambered in 38 special.
The Export guns (Brazil export) were made in even smaller numbers and would command a premium to the right individual.
Here's a pic of a standard 357 Mag 2 1/2" gun:
