I think it's a really great deal and I personally paid $20 to go to all the starving indie developers. The reasoning was that if I saw any of these games on Steam for $5, I would probably buy it, but I wasn't sure if all the games would be worth it so I paid for about 4 of them. I already bought World of Goo and liked that game a lot. I think a fraction of what I paid for the bundle is probably worth just that game.
There's less than 24 hours left on the sale so I think you should go out there and support the indie gaming scene before it gets swallowed up by PopCap and the like.