Pricing for flats vary but as of early 2010 one common going rate for a flatted page was $15 if the page were inked and of regular difficulty ($30 for a double page) with $20 for a sketched page of regular difficulty ($40 for a double sketched page).
Because each colorist has preferences as to how the flats are to be done flatters usually work as freelancers commissioned directly by the colorist.