I have a flemish giant that stays in an extra large dog cage when I am not home or in bed. The rest of the time he has free run of a room. I purchased the cage on ebay. It was new, took 3 days to arrive and cost me I believe $60 including shipping.
You could also look in to building a cage from an X pen. I have two smaller buns that share an extra large dog cage. On the outside of this I have set up an X pen for when they get out to run around. Again I purchased it new on ebay for about $70 including shipping. It is 48" tall. At first I did have it set up as a cage but everything I tried to use as flooring they chewed that is when I purchased them a dog cage. With the X pen set up as a rectangle cage it measured 7' X 27".
Another good option is building a cage using nic cubes.