A search revealed further background information:
Mandis owe their development partly to government policies on agricultural marketing and are primarily wholesale markets, located near important towns or centres of production. They are usually governed by APMC (Agricultural Produce Marketing Committee) Acts
Small farmers have limited access to these mandis. Transactions take place between commission agents and wholesalers. Market intermediaries purchase the farm produce from farmers, often in advance, and bring it to mandis for sale to wholesalers.
Unlike the regulated markets, there are also unregulated markets known as haats, peta, angadi, hatwari, shandies, chindies or painths. These are sometimes periodic (once a week) and sometimes permanent. Figures on haats are difficult to obtain.
But there are believed to be around 47,000 permanent haats, mostly concentrated in Bihar (including Jharkhand), Kerala, Madhya Pradesh (including Chhattisgarh), Maharashtra, Orissa, Uttar Pradesh (including Uttaranchal) and West Bengal, all relatively backward parts of the country.
In haats, there is an opportunity for producers to directly sell to consumers or small rural retailers, although APMC Acts sometimes prohibit such sales that bypass mandis. Unlike mandis, small farmers have access to haats. Local bodies usually control auctions of space and issue licences and permits to vendors to use these haats.
Market fees or taxes are collected from the participants, but these are rarely ploughed back to develop infrastructure. Haats are not equipped with basic facilities like platforms for sale or auction, electricity, drinking water, facilities for grading, sorting and so on. It will cost less than Rs 1 crore to upgrade a haat. And that will be true Bharat Nirman.