Here is a list of payment gateways that you can add to your checkout to take payments.
Afterpay
DPS (Windcave)
Laybuy
Ninja Pay (Via Fat Zebra)
PayPal
Stripe
ZipPay
Please contact support for the implementation cost. You can email support@webninja.com.au or create a ticket here https://webninja-support.zendesk.com/hc/en-us/requests/new