Grab a few of these $4.59 line follower kits
before the price goes up, they were $4.36 when I bought on March 31. Once again, the sum of the parts is worth more than that! It's not programmable, just uses an LM393 comparator and two CdS cells to follow a line. Quick & easy build, works right away. It zigzags (alternating left/right motors) in its stock configuration, but I tweaked it and it's smoother & faster now. My video on top, someone else's at bottom.