Don't forget that "self sustainable" would be a pipe dream - there's no conceivable possibility of producing advanced machinery such as electronics on Mars given current or near-future technology.

Also, there's a very good chance that this type of exploration of Mars will forever contaminate it preventing us from using Mars to explore the origins of biological life, a much more important and achievable goal than space colonization, and one that doesn't shut out the other one in a farther future.