Hey guys, i want to build a line following robot and I was scouring ebay for some sensors
I found these but I wasn't sure if they would work, as I haven't done this before. They're pretty cheap.
Thanks Basile, and the LMR community.
I was just thinking.
Once you get the sensors, you could feed the outputs to a specific set of resistors and read the whole batch on an analog pin to figure out where the line is. 
Treat them like a switch matrix being read on an analog pin.
They are a good choice to
They are a good choice to short distance like you need it for a line follower. I am using one in my R2D2 clone https://www.robotshop.com/letsmakerobots/node/31848 and get a max. trigger distance of about 10-15mm depending on the light conditions. less than 5US$ for 10 of them is a good deal.
Just be careful, add the current limiter resistors or the LED will burn very soon 