Cha Am, 30 minutes north of HH. Nice and relaxed, fairly 'Thai' and budget accommodation available. Can get busy at weekends and national holidays, but so does (all of) Prachuap.
You can get reasonable and cheap digs in Pattaya and it can be a cheap place to live if you steer clear of the bars and gogogirls. Unfortunately you have to travel out of town if you want to swim in the sea.