I was not aware of this. It is not open-source though, and it is really just for research purposes.
Its actually quite impressive how much they've implemented, though it is still a small fraction of the software you'd need to run an actual cell network.
It's also not "they", as it's been developed by a single programmer. Certainly, Bellard is no ordinary programmer, but this should still give some perspective to your claim of the millions of dollars required for development.
http://bellard.org/lte/