Bangkok isn't itself a cruise port, but is served by the port of Laem Chabang. Combined, the cruise port of Laem Chabang serves as the point of embarkation for one cruises anually from Norwegian to Asia.
On average Bangkok is moderately affordable compared to other ports. Check the diagram below for the monthly average cost per day (Cruises only depart from Bangkok between February and February). Prices are roughly the same throughout the year.