Problem with LARGE files

[Chris Jefferson <chris.jefferson@comlab.ox.ac.uk>]

I am currently finishing work on a program which can be used to  
identify a group of mathematical structures. I would like to release  
it under the GPL. However building the program involves applying a  
lossy compression algorithm to around 400GB of data files, turning  
them into about 50MB.

I could possibly write a program which, using this 50MB could back  
the 400GB data set I have on my hard disc, but this would probably  
take around four months to run.

Would it be reasonable to request someone had to spend £100 on an  
external hard disc and postage if they wanted to request the "source"  
to my program? and is there any way I could ever get such a program  
into Debian? Perhaps a different license?

Thank you.

PS Please CC me, I am not subscribed to the list