[MrE]

BlueFire is your least expensive option, and from everything I've read, totally adequate. You already have a diagnostic port in the drivers area, but it's probably a 12 pin DDEC port, the BlueFire requires a 9 pin J1939 diagnostic port. You can either get an adapter, or buy a J1939 diagnostic port and wire it in yourself. There are only 4 wires necessary, CAN high, CAN low, and 12v positive and a negative. PM me with your email address if you want the options broken down.