How to reach pattaya from suvarnbhumi airport?

I'm traveling to bangkok from 12th to 16th oct..I'll b staying in pattaya only..on very tight budget.I'll b reaching bangkok airport at 10-30 in morning.I'll prefer bus in any case.because spending 2500 bahts for taxi is too costly for me,to be honest.Also, please suggest me how can i come back from pattaya?my return journey is on 16th october...flight timing is 5 pm in evening.Kindly help me.Thanx in advance.