This can be a complicated but nifty little trick that not everyone will know. This will NOT work on pre-saved games.

Open the file C:Program FilesLionhead StudiosBlack & White 2DataBalanceGameBalanceArtefact

copy the file to a safe location--you may need it later. once you have done this, open the file stored in the directory listed above. You will see the values for everything on the tribute menu. Look for something similar to this:

ARTEFACT_EPIC_WONDER_NUMBER_VOLCANO 100000
disregard the other numbers. change the value directly to the right of any artefact and you WILL change it's tribute cost in the game. Do not change it below 1000 because it may not work properly. You can do this with every one, but make sure to change the total cost at the end of the file to whatever it now ads up to.

Go to your game folder and navigate to DataBalance. Find the file PlacementData.xml and open it in Wordpad. Find the third paragraph, which starts