If really blued, and really in excellent condition, I'd say $600-700 is OK. Below this, I'd say it is good, and anything below $500 should be pounced on.
I did see one lately on gunbroker that was said to be excellent, but it was NOT.
IN the mid eighties they were mostly enamel, but some blued and some parked as well. Blue in excellent condition is likely the most valuable. They are scarce but not rare.