2) Sign treaties with Russia, build pipelines from Syberia to China. At least, in this way, China may be able to get cheaper priced oil. And probably buy them without using USD.
3) Find oil locally. But that's not very hopeful. China is not a oil rich nation, unfortunately.
4) Develop nuclear power capability to eventuall supplement or replace crude oil.
However, for now, China has to spend 7 times more money to buy them from the Saudis on open market. Well, when China pays Saudis, the money will end up in US' pocket sooner or later.