GP - At the entrance to Gold Saucer, near the save point, there's a man who appears who will actually sell you GP. The chance of him being there is about 1/60 I think, just buy a Gold Ticket then run in and out of the Gold Saucer entrance until he's there.

Lure - Only two in the game unfortunatly, one at the beginning for 2500 gil (unless you did the save/reload trick or powerlevelled you did buy this) and at the bottom-right corner of the screen on the floor by the chocobo pen (I think you can only get this one once you got the Highwind). If you've lost both of them I think you're pretty screwed.