Hello,
Yes you would be right. You could but locating them is a different story. As you said yourself you can not find them on NewEgg cause you would haev to be a partner or reseller to obtain them i believe. I have not seen mobile GFX cards for sale anywhere.
Staying in the same line would work. But you would have to rip apart the laptop which is where my caution comes in. Those ribbon cables tear and break easily. Considering that laptop mobo's are split. They are then sandwidched together. From my experience. So you would have to remove hard of the mobo without breaking any connections. Then remove the heatsink and CPU to replace it.
All in all you could do it. To many people it isnt worth the extra costs to find hte mobile stuff needed to fit and owrk properly in a laptop. Getting a new CPU isnt just like popping it in. Have to find one with low heat so that you dont cook the laptop.
But with enough want you could do it. It will just cost you more to upgrade a laptop.
Cheers,
Mak