$550
Find one for sale and buy it.
The Internet.
Dangerous game
Hunting, shooting, collecting.
Made by who, you need to state who makes it.
A VERY large caliber, VERY powerful rifle. It is the .577 T-Rex.
While the 4 gauge shotgun has a larger bore diameter, it was originally a black powder cartridge, and operates at much lower pressures than a modern high powered rifle. The 577 T Rex has much higher energy,
Here is a good article for you- http://en.wikipedia.org/wiki/.577/450_Martini-Henry
Possibly the .460 Weatherby Magnum, the .577 T-Rex, or the .700 Nitro Express.
Assuming you mean the .577 T Rex (there are other 577s) they are custom made by A Square. You would order one of the several thousand dollar rifles, pay for it, and on completion it would be shipped to a dealer in your home state for transfer to you. Base price WAS $4,050, plus travel to their shop for fitting of the rifle.
100-multiple thousands depending on EXACTLY what it is, history, etc.. Seek a professional's help
1 x 577, 577 x 1