5-channel IR line sensor plus front (?) IR proximity sensor plus bump switch in one package for about $3.15 USD shipped (Oh, plus tax now!). Might need a bit of rework since the front IR sensors hit the wall before the microswitch.
But an interesting little sensor array, all wired up to a convenient connector. https://www.ebay.com/itm/223263216001
I for one, would love to see a Boebot/Activity bot with high speed servos do impressive speeds on a line following course. It would take a sensor like this to do so.
BTW, there are those who consider line-following as the "holy grail" of robotics: https://www.wiltronics.com.au/MeetEdison/
, about a quarter way down the page.