Reddit mentions of HC-020K Double Speed Measuring Module with Photoelectric Encoders For Experiment

Would this work for you?
https://www.amazon.com/gp/product/B00EERJDY4/

H-Bridge (for the UNO there are also shields)

Sensors e.g. this / that though you can also get tctr5000 modules for cents elsewhere.

And note that if you are not set on a line-follower, the kit you've chosen already includes the ultrasonic distance sensor which is nie for robotic projects as well :-)

Do you have a soldering iron and multimeter? Even a cheap $4 multimeter is fine for low-current & low-voltage tasks, and makes your life easier (checking voltages, connections, resistor values...)

As for a soldering iron, even a $1 will do (if it doesn't burn down your house ;-) ) - but an adjustable temperature one will be more worthwhile. Even a $20 soldering station will do to get started if you don't want to spend $80-$100. I tried to avoid soldering for years, and it was a big mistake. It's actually easy and useful.


And another note: The 2wd and 4wd chars will not always go in a straight line. Motors don't run 100% in sync, even at the same voltage.

With a rotary encoder you can ajust the speed in software. You can use one of those IR reflective sensors modules, or a gap sensor, or even a hall sensor... example


You can also get 2wd kits example, but overall, they aren't as great of a value (and as you can see, they just include the standard modules)

A "sensor shield" like in that kit is nice though as it reduces the wiring chaos a bit :-) They cost $1 for the UNO at Aliexpress, probably more expensive at Amazon.