Since it takes a whole ham, much of which gets discarded, to make a culatello, culatello is expensive (true, the cuttings are used to make other things, but they're worth much less than prosciutto). It's also becoming more difficult to find true artisinal culatello, because the farm buildings and the mists essential to its production are frowned upon by the health people of the EEU -- they're not sanitary enough. That the production of culatello dates back centuries, to the time an apprentice is said to have made a mistake while trimming a ham destined to become prosciutto (he cured what he was able to salvage), and that it has never made anyone sick is of little importance to the regulators.
Though you may find strictly artisinal culatello produced elsewhere in the Bassa Parmense, the best known culatello is Culatello di Zibello (link in Italian), which is produced in and around the town of Zibello; Culatello di Zibello has been recognized by the EEU and granted DOP status (the equivalent of an appellation, but for foodstuffs)
A general overview of salumi, Italian cold cuts.
Affettati Misti, a mixed cold cut antipasto