How exactly do you know they don't cost a couple of million to make? Not only do they have to recode the game to be able to make it work on the PS3's architecture, but they also rework the textures to give it a HD facelift. In the case of FFX/X-2, they are making content that was never available before in North America actually available (not sure if Last Mission in X-2 was available in Europe, but I know X International content was).
The same is true for PSOne games. They have to do some kind of coding to make it work on the PSN, although all PS3s are backwards compatible with PSOne games.
As for the HD Collections being overpriced, go ahead and find some of those PS2 games. I remember that the PS2 versions of ICO and SotC were ridiculously overpriced by people on eBay, so being able to get both of those with upgraded visuals and trophies (some people like this) for only $40 (I got it for $25 close to its release) is a lot better. You can get a lot of the collections for a lot cheaper in 3-4 months if you would like, or you could spend more money to hunt down each individual game on its original system.
