local bus to surathani(i take it your not stayin in phuket????)cheapest way.
Why are u flying into phuket and heading over to the east side,im baffled,why not samui,hell of alot easier,probably cheaper,youve got some explaining to do fella.
what i would say,if u are staying phuket a while before,u can arrange a minibus and boat,all in one to phanghan,around 400b if u look around,but of course cheaper still,take local bus to surrathani,probs no more than 100b,but then from surathani u would have to arrange a taxi an hour down the road to the port(cant remember the name),then u could purchase your ticket there for the boat,a little more than 100b i think.
there will be plenty of people to help u out in surathani,agencies etc....can give u transport to port and boat ticket deal...just depends how u wanna do it....have a good one