The expansions are no longer available for individual sale, as GC2 Ultimate is now priced at the same point as they were individually (lower even, since it's currently on sale everywhere).

Unless they patched it without my noticing, some of the changes that come with the Ultimate edition (such as ships with multiple weapons being able to fire upon more than one ship per combat round if the have multiple weapons and destroy the first ship) have made some of the Dread Lords campaigns very much harder than they were originally.  Before, the way the destroy a Dread Lords ship was to have huge fleets of tiny ships, and the Dread Lord ship could only destroy one per combat round, but now, a Dread Lords ship with multiple weapons can destroy many of your tiny fighters per round.  The result?  The tactic of engaging a Single Dread Lord ship with multiple tiny ships no longer works so well, as many get destroyed each round instead of just one.  Without that strategy, taking on the Dread Lords in the campaign is very, very, very difficult.