Litho printing invariably has a costly set-up charge. Pages have to be imposed onto printing plates, and the press has to be set up afresh for each plate. The platemaking machinery and the press are sophisticated and expensive, the operators are highly skilled. These overheads have to be covered before the job starts to print. Once the preparations are made the press runs quickly, and the ongoing costs are not so great. Unit costs become reasonable at quantities of 500 or 1000, and really start to level out at 5000 or more.
The quality varies with the cost and size of the press. A small press, carefully maintained, can produce good work, but illustrations may not be of the highest quality. To achieve top quality a larger press is necessary, and the overheads of paragraph one become dominant.
A litho press can print in any one colour, depending on the ink put onto it: black, or blue, or whatever. Changing the colour of the ink can be time-consuming, adding further to the set-up costs of a "two colour" job. Such a job can easily cost more than twice the cost of a single colour run: although the same paper is used twice everything else, plus the cleaning, plus the extra care to ensure the two jobs are printed in good register, adds to the bill.
If four presses are bolted together, and synchronised, they can print with four standard colours of inks to produce "full colour" work. Such presses are commonplace, require four times the costs of paragraph one, above, to set up and usually need to run all day (and night) in order to repay their capital costs. Six, or eight, even twelve, presses can be joined together.
Printing plates can be made by photography (camera-ready-copy, crc), or (increasingly common) from a computer-operated plate-maker. This latter case is, regrettably, not a simple matter of using your "ready to print" files.