Price is influenced by server workload from number of captchas and number of workers online. The price is the same for all webmasters at the same moment and ranges from 0,5$ to 1$. You can check current rate by API or at 2captcha API. Webmaster can adjust his maximum rate per captcha. When the rate is higher than set by the webmaster captchas wouldn't be uploaded and webmaster will receive :ERROR_NO_SLOT_AVAILABLE:
To receive refund webmaster has to inform server about incorrect recognition. Either through reportbad function or manually by clicking “incorrect recognition” on the “loaded captchas” page. Complaint must be issued during 15 minute gap starting from the upload of the image. After that server wouldn’t accept the complain and will return ERROR_WRONG_CAPTCHA_ID. After an issued complaint worker’s account is bloked for the sum of the complaint and worker has 2 days to dispute the complaint or to agree with the blocked sum for incorrect recognition. After 2 days money for incorrectly recognized captchas is returned to webmaster, excluding cases when worker disputed webmaster’s decision and moderators agreed with workers position.