FLC OF COMMUTER ALLEGEDLY CUT OFF ACFT ON SHORT FINAL.

Narrative

WHILE TAXIING FOR TKOF ON RWY 30 AT VIS WE HEARD TFC RPT HILAN INTXN ON THE ILS AT VIS. I DID NOT THINK IT WAS; BUT CHKED THE CHART TO BE SURE; WHETHER HILAN WAS ON THE APCH TO VIS; IT IS NOT. SO WE WERE NOT SURE WHERE THE TFC WAS. ARRIVING AT THE END OF THE RWY A FEW SECONDS LATER AND SEEING NO TFC; WE RPTED WE WERE DEPARTING RWY 30 ON UNICOM. AS WE WERE ROUNDING THE CORNER TO TURN ONTO THE RWY TFC CALLED HE WAS INSIDE THE MARKER. WE SAW THE TFC AND HE LOOKED ABOUT 3 MI OUT. AFTER XING THE RWY HOLD LINES AND JUST ENTERING THE RWY WE SPOTTED NON COMMUNICATING CROP DUSTER ON ABOUT A 1/8 MI L BASE ABOUT 100 AGL. WE STOPPED AS WE DID NOT KNOW HIS INTENTIONS. THE CROP DUSTER THEN TURNED SHARPLY AWAY JUST BEFORE FINAL. WE THEN DECIDED HE MUST BE DUSTING AND NOT LNDG. WITH THE OTHER INBOUND TFC ON ABOUT A MI FINAL WE CONTINUED THE REST OF THE WAY ONTO THE RWY AND DEPARTED. AFTER DEP AN ACFT PLT ASKED FOR OUR NUMBER SAYING WE HAD JUST CUT HIM OFF. HAD IT NOT BEEN FOR THE CROP DUSTER; WHOSE INTENTIONS WE DID NOT KNOW; WE WOULD HAVE DEPARTED WITH ABOUT 2 MI SEPARATION. SINCE WE WERE ALREADY PARTLY ON THE RWY AND WE HAD SUFFICIENT SEPARATION; WE DEPARTED.