More complex motor controllers may be used to accurately control the speed and torque of the connected motor (or motors) and may be part of closed loop control systems for precise positioning of a driven machine.
The street price for a gold bar is: 180-190 gp. The price in a specialty store is: 381 gp. If you buy from a general store, the price is 180 gp. If you sell to a general store, the price is 120 gp. In the Grand Exchange, the market price is 204 gp, 194 gp minimum, and 214 gp as the maximum price.
Time change and nowadays there is a tremendous variety of gold bullion in the form of solid gold coins and bars from many mints and countries. You can now buy gold bullion bars as small as 1 gram or a 20th of a troy ounce. Of course buying gold in such small quantities is not very practical as the cost is so high.