Currently in the official NC soft store, the prices for the gw trilogy are $29.99 while each campaign is also $29.99 except eotn is $19.99.
Now this post isn't for me, I've been playing guild wars for 5+ years, pre-ordered every expansion at full price etc except prophecies. But I know several "returning" players who want to do their hom and stuff and get ready for gw2, but don't have all the campaigns. Now all of them already own at least 1 or 2 campaigns. Its silly to think that it would be cheaper for them to buy a whole new trilogy, than to buy just factions + nightfall. Why should existing players be punished like this? And even if you think punishment is to strong a word, if anet wants to give discounts to new players go ahead etc, that's fine and all, but you would think they would also want to sell as much as their product as they could. The games have been out for several years... its only natural to cut prices some more.
As it stands several of my friends would 1) rather not buy the expansions, b/c they feel its to expensive and a waste of money compared to just buying the whole set (but then they lose their toons, armor, $, whatever else they had from their original game) or 2) buy it from some other site for $9.99, now I have no idea if buying from a store site (like gamestop) is against the user license agreement or not, but pretty sure buying it from a place like ebay, amazon, etc from other players is against it, plus there's always the risk that the cd-key won't work b/c its been used already, that sort of thing.
I'm pretty sure a lot of the guru community will be like /notsigned, i paid full price, so should they, b/c i've seen that type of mindset in other threads a lot, but guess what, I paid full price too... and I'm signing this because it seems like a great idea I had

My suggested prices are:
Prophecies, Factions, Nightfall: $19 or $14.99 each
Eotn: $14.99 or $9.99