How to get from Bangkok to Koh Samui on a budget

Here is a brief extract from Steph's original article:

• Flying is fastest and easiest way to get to Koh Samui is to fly from Bangkok, but also more expensive
• Tickets are normally around US$100, cheaper if you book early
• There are about 19 daily direct flights
• Alternatively, to save money, you can take the budget airline from Bangkok to Surat Thani, and then ferry to Koh Samui.
• This way is cheaper but also takes longer, total transit time is 3-4 hours
• Nok Air sells a combo which included the plane, bus, and ferry - still cheaper than flying to Koh Samui directly