In April 2004 I flew from U-Tapao (Pattaya) to Phuket, via Koh Samui.
They stopped to pick up the very people you would be relevent to. The entire trip cost me only THB2390.
We were off-loaded at the nice low profile grass-hut terminal at Koh Samui for about 45 minutes, to allow for the loading of the Samui - Phuket passenger luggage etc.
I don't know what the leg from Samui to Phuket costs, but my total shown above from U-Tapao, which is about an hour by bus from Pattaya, was very cheap.
Cheers
Pdm3
