The SmartyCam is expensive, yes. I use both as I bought my GoPro originally to record Moto-X, then surfing (boogie board), and finally karting. Thrilled with the recordings, I started watching the karting videos on youtube and came across the SmartCam.
ith the accelerometer, GPS, and the SmartyCam software you combine the Mychron with the SmartCam and watch all telemetry overlaid on the video. The GPS lets you skip any beacon setup as well as define your own points, in addition to simple lap times. You can make your own splits and watch the straightaway times, and any other sections you wish to define and monitor.
Especially since this is your first year, you need a mychron and a camera. I recommend paying up for the smartycam and skip the gopro unless you need it for other activities.