They could...
Why couldn't AMD port their own 90nm process to 300mm? Why must it be identical to IBM's?
but it would be very expensive, and would take more time. I would put that effort closer to $500M than the $200M to transfer it from IBM, but then I am just making an educated guess.
They could copy their existing 90nm process, and buy equipment similar to what is in fab 30 to minimize the R&D expense, but then it is unlikely that equipment would be usable to copy the IBM 65nm process. This would be a huge capital expense that would have a very short lifetime.
Keep in mind that fab 30 uses equipment that is about 5 years old, while IBM has mostly 2 year old stuff... and the IBM equipment is outfitted for 300mm while the AMD fab 30 stuff is likely 200mm only.
Intel did this with their 300mm start-up where they made both a 300mm and a 200mm version of the 130nm process. They indicated that it was a totally new process development and they could not use copy exactly for this... They could only develop modules that essentially mimiced the 200mm results. Of course a $500M insurance policy for Intel is affordable, while for AMD it is unreasonable.
--Alan