While Marik is a huge production center for IS 'mechs, they sell most of them to other powers. let's look at the examples given:
the Cicada was sold in huge numbers to Kurita and Davion from the beginning of the Clan invasion;
the Centurion is built by Corean Enterprises in both Davion and Marik space, and is considered an archetypal Davion 'mech;
the Hunchback is built in Marik space, but was already heavily favored by Kurita forces by the early 3020s;
the Trebuchet is actually an identifiable Marik 'mech;
the Awesome and Stalker are so ubiquitous that they are even found in Periphery regiments.
That's the background, which you can find in
TRO3039 and
TRO3050U: in MW:O, it has been mentioned that all 'mechs will be available to everyone, but that Houses will be given price breaks on specific 'mechs.
Nonetheless, this is a good list, but you'll usually find that the Free Worlds League produces most of the 'mechs, irrespective of who uses them.
BTW, while the Cataphract is a Liao design, the production plant was lost to Davion during the Fourth Succession War, during which (so before our current game year of 3049), it became a Davion-produced 'mech.
Edited by Major Bill Curtis, 23 June 2012 - 08:20 AM.