Sorry, but I do not believe this will be cheaper than conventional rail. This is essentially a vacuum tunnel. Ok it is not a perfect vacuum but it is still supposed to keep 1/1000th of the earth's pressure.* Keeping such a vacuum over several hundred miles of metal tubing would be very very expensive.

This may work but it will be several times more expensive than the HSR system.

* Oh and by the way, it is completely misleading and annoying for musk to refer to this as merely 1/6th of Mars's pressure. That would be a really relevant statistic if he was building his thing on mars.