A friend of mine reminded me of an option for mars... von neumann machine, gathering all needed materials and fuels form the actual place, but we need to enhance technology a bit more to do that...
AI, fusion plants, materials & material related procedures (probaby also nanotechnology, that would give a big deal of help to the "big bots") and so on.

Also in this case I belive true von neumann probes would not be in the context, since it would be far easyer to make a not so AI dependant, more like preprogrammed bots specialised for each task. and eventually an (bot built) universal bot factory that can be programmed from earth to construct any bots needed for any task that might be encountered or needed (of course resource gathering and preparation of them would be the mayor need of new technologies)
And at higher level of the proyects completion there would be needed a great contribution by various programmers and designers from earth.


some info here:
http://en.wikipedia.org/wiki/Von_Neumann_probe


After all this work and development (estimated to be an about 100yr proyect) as this friend of mine said... we would yust walk onto mars with all the infrastructures, housing and appliances waiting for us


(u ppl like SF? This post is lots like SF so u don't need to argue with "this is bulls*it"-like comments, better get in the role and post some kewl comments/suggestions)

Main expense would be paying the ppl on earth, the beginning would be just a few startup bots, and solar panels to provide the energy to power up those bots the rest would all be made by "free resources & energy" gathered and produced from mars raw materials and energy produced there, so paying the pll to develop and supervise the progress would be the biggest part (unless u use a huge deal of "free" developers (read: free software, gnu...)) in that case u would have to pay only the coordinators & supervisors