I commonly bought expansion packs “back in the day,” because hey, a new campaign, a new race, ten new maps, ten new units, another full “main quest,” a couple of new pre-rendered plot movies, some new multiplayer modes, and a new gun to boot sounded like a pretty damned good deal at $20-30.
Civilization V, on the other hand, is a ridiculous rip-off. $5 for a single new race with one new unit (variation of existing) and one new building (variation of existing), plus about 30 seconds of leader animation? In a game where there are dozens of units and buildings and races already for $50 (as I did buy it day-and-date)? This is nothing more than pure nickel-and-diming of the worst sort, and I cannot imagine supporting it.
Now, if they release all the new DLC civs and scenario packs together in a “pack” (that expands, one could say) for $20? Sure, I’d at least begin to consider it. But think of how much you got when you bought Civ 4 x-packs like Warlords or, especially, Beyond the Sword, and how much that cost. Value per dollar has plummeted ever since easily purchasable microtransactions (and be a pedant if you want, but I don’t see a lot of difference between a $2 skin in a FTP MMO and a $5 civ in Civ 5) came to the fore.
So yeah, I guess I can say that I agree with several other posters insofar as “if it adds significant value to the game, I’ll buy it at the right price,” with the notation that my threshold for value is much higher and my limit on price is much lower.
Want to see “DLC” done right? If Starcraft 2’s “Heart of the Swarm” launches at $30, that’s a value, assuming the facts remain that it will still include a new (and lengthy) campaign complete with new advancement mechanics, animations, characters, voice acting, movies, units, and missions, as well as a healthy stock of engine improvements, mapmaker enhancements, Battle.net features, and multiplayer units and maps.