VHG is correct in that most laser printers are supplied with toner cartridges that are not full – and may be only 25% full or less (the same is true for ink jet printers).
Before buying a particular laser printer, check out the cost of the cartridges and the number of prints you can expect. Most reputable manufacturers will give an expected print volume based on a 5% image (which is typical for a typed document, not photos etc).
Although laser printers may cost more than ink jet printers; the toner cost can be a low as 1p per page for a laser printer compared with around 5p per page for an ink jet.