The Turkish e-Visa is an official document permitting entry into and travel within Turkey.
Applicants obtain their visas electronically after entering required information online and making payments by a credit or debit card (Mastercard, Visa or Paypal).
You need to have a travel document (passport) valid for at least 6 (six) months from the date you intend to enter Turkey.
Depending on your nationality, there may be additional requirements.
The fee actually depends on your nationality.
You can apply here: https://turkishvisa.com/