Printer/hardware for making posters?

[Joduko]

I'm looking to make posters to sell and I'm doing some research as to what exactly you need to do this.

 

All the really big printers seem to be by HP or Canon. Are these what I should be looking at?

 

And for whichever printer is best, how do you go about acquiring refills on ink? Cartridges you can refill from a jug like paint or something?
 

And the last big question I can think of is what kind of paper or other material is best to make posters out of? Looking at most of the posters I've ever owned the paper is not like ordinary office printer paper.