A lot of information. You can make comparisons without going to many merchants to find out the price of a certain item, which will cost you a lot of time.
Large amount of information. For comparison, you don't need to go to many businesses to understand the price of a commodity, which takes you a lot of time.
A large amount of information. For comparison, you don't have to go to many shops to find out the price of a certain commodity, which takes you a lot of time.