Bringing weight to orbit is expensive. In a long term, there is a risk of collision with space debris.
Agreed that bringing mass into orbit costs something, as does protecting that mass from the dangers of space (e.g., debris). Bringing mass to Antarctica costs something, too, as does protecting that mass from the dangers of Antarctica (e.g., weather).
It may well be that orbit is more expensive than Antarctica.
But if bringing mass to Antarctica is worthwhile because the energy savings associated with the average temperature differential between Antarctica and wherever the brains were initially cryopreserved offsets the upfront costs, it may well be that the greater temperature differential between space and wherever the brains were initially cryopreserved would similarly offset the greater upfront costs.
Potentially of interest to my fellow antipodean LessWrongers. Stasis Systems Australia is a company seeking to start a cryonics facility in Australia. Their website is pretty sparse, but they just sent out a mailing list update on how they are going, and it doesn't appear that the information therein is located in any news section of the website, so I thought I'd post it here.