I'm assuming this is waist-up, because that's what I generally assume when I hear talksprites because I'm an ex-homestuck, and a simple character. correct me if i'm wrong!
it can be either smooth rendered or pixelated, but if you want it pixelated, since it's not small-scale pixel art work, i just treat it as working with a different brush, so it's the same price as a normal render.
Math time!
Depending on what level of completion you want: two-thirds of the base price for the first expression, and 20% of base price for each expression after that-- which, for five expressions, will be the original base price.
(ex: for ink+flats, [$6 base] + ([$1.80 per expression] x [5 additional expressions]) = $15
for basic cel shading, [$8 base] + ([$2.40 per expression] x5) = $20)