Minecraft limited supplies

So we (me and my buddy) just lost a few diamond pieces, obsidian and tons of iron to lava :(. How much can you find in the world? Is it worth starting over if you have lost some?

The world size in Minecraft isn't finite; Technically there is an infinite amount of diamond. There's more than enough, it's just a pain to find.

Also, if you want to play illegitimately:[Misc] Cheat engine for blocks, sky and fog. You could cheat and spawn what ever blocks you damn well please. Takes the fun out of the game, though.