Epic price, RRP is around $200 for the HU alone. Supercheap is selling the HU for ~$100, speakers would be worth another $50 on their own i'm guessing.
Overview
Slot-In CD/MP3/WMA/Tuner player. Includes 16cm 2-Way Coaxial Speakers.
Key Features
Frontal Aux-In
52W x 4
Pre-Out: Rear/Sub switchable
Speaker Peak/Rated Input Power: 190W/40W
On sale now!
I asked the same naive question regarding the stocks in my car a few posts up. It is difficult to say because the sound quality of stock speakers can be highly variable but there is also an element of subjectivity("it sounds good to my ears" or "that is awful".) The RMS rating is most likely higher on these speakers which means more power and louder volumes without distortion. You will also get more clarity, deeper bass and dynamic range because they are 2-way speakers.