Commissary is a store that the jail or prison runs for the inmates. You can purchase items with money that you have on your inmate account. If you do not have any money or your account the jail or prison will provide you with an indigent package, which consists of hygiene products.
The commissary store schedule is usually once a week. An inmate would typically spend around $25 a week. This would usually be a good amount of food and any other items an inmate needed. As you can see there is a good variety and most items are reasonably priced.
One item we suggest you buy on your first store trip is medicine. Pick up a pain killer, cough syrup, and cough drops. There is no worse place to be sick than prison. And, with all the inmates in close contact you will get sick at least once a year.
Another item that we would suggest is pre-stamped envelopes. You can never have to many envelopes. The reason for this is that they can be traded for other items. These are almost like cash in prison because they are priced right around $0.50. This makes trades very easy, but do not get caught by prison guards. Trading commissary goods is against prison policy.
Commissary is a privilege while you are in jail or prison. If you have any incident that involves disciplinary action they will revoke your commissary. This is one of the most common punishments. Remember, your already in a tough spot, don’t make it any more difficult on yourself.
You can have a look at a sample of the Metropolitan Detention Center (MDC) Brooklyn commissary sheet: http://www.bop.gov/locations/institutions/bro/BRO_CommList.pdf
Items are going to vary greatly across facilities and times of the year. This is just to give you a good idea of what is available.