All you have to do to have a Mac Pro that burns Blu-Ray Discs is go to Apple's Website, use the student discount, and configure it to have 2x 2.0 GHz Dual-Core processors and a 160GB HD. Then, buy a Blu-Ray burning drive for $699 from this site.
Mac Pro $1969
Blu-Ray Drive $699
Grand Total $2668
However, you may want to wait until the next gen Mac Pro is released because it may already have Blu-Ray capabilities built-in.