I'm planning a day trip to Macau from Hong Kong, what's the cheapest ferry I should take?

You can take the economy class cabin of the ferry at HK-M Ferry Terminal or China Ferry Terminal. It costs 159HKD per person and should be the cheapest price.

Upon your arrival at M ferry terminal, you can take the free shuttle bus to Venetian Resort. Then walk to nearby M University of Science and Technology Station to take bus no. 21 to the sightseeing tower. After that, you can walk to find bus no. 9A or 23 to Ruins of At. Paul, and then walk to Senado Square (or take a taxi to reach with the fare within 25MOP).