I too bought an Elegoo kit. It's good bang for the buck IMO. Amazon.
For discrete components I like Mouser for their massive selection. Also have a few good retail parts houses by me.
Get friendly with your local RC hobby shop, too. They have gigatons of stuff that crosses over into the robotics realm and staff who are happy to help you with some of the more mechanical side of things.
If you're building robots, also check out Superdroid. This place has it all and then some!
this link https://www.superdroidrobots.com/store/robot-parts/electrical-parts/motor-controllers?page=2 has my favourite motor controller on it, the sabertooth.
Since this is for college though, I'd wait to see what the program curriculum has in store before buying a bunch of parts willy nilly. Suppose you get the Elegoo kit with one of each type of common sensor, one servo, one stepper etc. I never went to school for any of this stuff but two things come to mind anyway: firstly, guys I knew who did typically got a list of what they should have in a kit (they all used tackle boxes, something I stole from them - the idea, not the gear) such as resistors, transistors, etc. Secondly, any robot-y type thing I've built (yes, robot-y is a technical term) has duplication on it of things that a kit probably won't have for any build.
So, for ex, when I made a Dalek, it used four ultrasonic sensors, not one. When I made a teleoperated robot prototype as a hazmat helper, it used lots of servos for the cameras, not one.
Finally, if this stuff is pretty new to you, rather than trying to get to know how to use every sensor under the sun before school, if you know you'll be using Arduino, get right with @Robin2 's outstanding tutorial on working with serial data. Trust me, if you aren't already strong here, you'll want to be.
https://forum.arduino.cc/t/serial-input-basics-updated/382007/3
This is the way.