We 办理过父母探亲医疗保险, just search the chinese newspapers (from Chinese superstore). And find a agent. (Sorry, I forgot his name, but I guess any agent can do that, no big differences.)
如何办理: call the agent
价钱大致在什么范围: it depends on your parents' age and health conditions.
Just call one of the agent, and you will know everything.