Take a look at what "forestall" used to mean:
"forestalling or regrating
Forestalling and regrating were similar offences in which middlemen purchased goods, particularly victuals, in order to resell them. Forestalling was the more serious, involving interception of goods en route to market (normally, before the hour when the market could legally begin business), in order to buy them and then bring them to market to sell at a price higher than for what they would originally have sold; or, since town authorities kept a close eye on market prices and could control them somewhat, the profiteering might be achieved by buying wholesale at lower than the current market price and then reselling close to the market price. Sometimes the purpose was artificially to create a shortage of goods, so that the "fair" price established in the marketplace would be higher than it ought. The seriousness of forestalling, as an infringement of community rights (viz. the right of all burgesses to have the opportunity to obtain sufficient supplies for household needs at the lowest cost possible), is reflected in the fact that the term -- meaning to intercept goods before they reached a market stall -- has a broader (metaphoric) application in modern vocabulary; the term "pre-empt", which has a similar meaning today, likewise derives from the purchase (Latin emptio) of goods before they could reach a public venue. However, commercial enterprise -- including the resale of goods by middlemen -- was fundamental to the economic character of towns, and regrating was controlled more via licencing and limitation than by suppression, while instances of forestalling constantly appear in borough court records."