Can I offer 2 different prices to my customer for the same invoice?

No, you are not able to offer 2 different prices to your customers for the same invoice.

Offering your customer a lower rate for paying cash/card compared to the finance option is against the Brighte policy.

This is also an issue with Finance Regulations and if you have are found to offer different prices, you could receive warnings from Australian governing bodies such as the ACCC.