Prices are negotiable and can be discussed on a project-by-project basis.
If all else fails, I usually try to work at $40 an hour at the standard rate and $20 an hour at the indie rate.
Rates are based on the following statistics collected by the Editorial Freelancer's Association and the International Game Developer's Association:
https://www.the-efa.org/rates/
https://gamewriting.org/2016/03/professional-rates-for-freelance-writers/

Type of Work

Indie Rate

Standard Rate

Cutscene Writing

NPC Dialogue

Editing

$60/1k words

$2/line

$5/1k words

$120/1k words

$4/line

$5/1k words