The experience you tell reminds me of a television program about a report on the large markets in China.They were huge in size so much that I needed a vehicle to be able to travel them.
In the town where I live there are not such large markets but there is an impressive variety of prices for dozens and quantities in mass.
In these cases it is very important to visit the site several times to get an idea of ​​the prices and to be able to make the right choice.