Phillipsburg, NJ Zip Code 08865 Lowest Regular Gas Prices Summary. There are 16 Regular gas price reports in the past 5 days in Phillipsburg, NJ Zip Code 08865. The average Regular gas price in Phillipsburg, NJ Zip Code 08865 is $2.34, which is $0.09 lower than U.S. national average Regular gas price $2.43. The lowest Regular gas price is $2.16 of US Gas located at 12 Union Sq, Phillipsburg, NJ 08865.