Need a solution to sent i2c data long distance (prefereably convert to CAN)
THe simplest/cheapest option would be a uProcessor with a CAN controller, plus a CAN transceiver chip (plus additional components to enable it to work) 

STM32F103RBT6 (£4.17 in 100off) + SN65HVD230D ( £1.53 in 100off) 

YOu need something that can interface to I2C and can communicate via CAN