What did england hope to buy from colonies at low prices?
England hoped to buy unrefined materials. Tobacco, indigo, ores, grain, wool, cotton, and sugar. These materials were abundant in the colonies, and highly sought after in England. In England they used tobacco to make cigars. Indigo was used to dye cloth blue. Ores were refined into metals for smithing. Grain was made into various foods, or made into liquors. Wool and Cotton were spun into thread, dyed, and woven into cloth. Sugar was used for various purposes too.
This system is called mercantilism. Colonies produced raw materials, like listed above, for relatively cheap prices due to supply and demand. They shipped these raw materials to homelands where there were factories and other processing facilities there. They made refined products, and shipped them back to the colonies.