The 25-year-old Price closed with an even-par 72 to match Killeen (76) at 5-under 283 on the difficult Greg Norman-designed Wente Vineyards course. They played the par-4 18th twice in the playoff, with both players parring the first extra hole.
Price earned $108,000 for the victory a year after tying for second behind Omar Uresti at Wente Vineyards. The former Georgia Southern player became the fourth Australian winner in the first six events this year, following Jarrod Lyle, Ewan Porter and Gavin Coles.
Joe Daley (73) was third at 4 under, former amateur star Colt Knost (72) was 1 under, and Fran Quinn (72) and Chris Nallen (73) followed at even par.
Knost, the U.S. Amateur winner last year at Olympic in San Francisco, received a sponsor exemption. The former SMU player, also the 2007 U.S. Amateur Public Links winner, gave up spots in the Masters, U.S. Open and British Open when he turned pro.