Buying a Tour in a Travel Agency in Los Angeles, can they get me the Chinese Visa?

I am a Guatemalan citizen and do live in Guatemala. But As I do have family in Los Angeles, its easier for me, to buy a Tour for China in Los Angeles. Guatemala does not have relations with the PRC. Can the Travel Agency at Los Angeles get me the entry permit? Or have to go anyway to San Jose Costa Rica?? which is expensier for me. Or could I get at Mexico DF?? which I can stop on my to Los Angeles and then to China.