Jack,
I was just over on gunbroker yesterday. I believe I saw a 3" barrel for a 686 for less than $100.
Buy your round butt gun and have the barrel changed by a gunsmith. At the same have him do a trigger job. I'm sure that there a quite a few 686 round butts out there, heck I just sold mine to buy my dream 4" 586. Good luck, have fun.
