I have a 2002 monte carlo I'm looking to upgrade a little. I recently had this head unit installed:

Kenwood - KDC-255U 22Wx4

I don't know anything about anything. Watts, ohms, flux capacitors

Budget for speakers is around $80, my speakers sound pretty good now is it worth it to upgrade with only this much?

From what I understand, the next logical step would be a set of decent speakers and an amp. I don't know what would be a good match to my current system, but I was looking into this amp:

Amazon.com: Alpine MRP-F300 4-Channel 300 Watts Amplifier: Electronics

As for speakers, maybe something in this price range:

Amazon.com : Pioneer TS-A1685R 6-1/2" / 6-3/4" 4-Way TS Series Coaxial Car Speakers : Component Vehicle Speaker Systems : Electronics

It seems my head unit is not very powerful (22Wx4) so I guess I'm not trying to go overkill. Again, coaxial, 4-way vs 3-way, I don't know what the difference is...