The normal discount price you pay for something at Wal Mart or Amazon.com. This is opposed to list price which occurs in manufacturers publications and on their web sites. Street price also refers to the price of goods which can not be legally purchased and must be purchased from someone on a street corner.
Although they list at $129, the street price on those shoes is $79.
The street price of a nickel bag is no longer $5. The street price for sex depends largely on what street you are on.