I don't want to use PayPal for people to pay their deposit - is there a way of setting up a bank transfer system without using the provided options?

You can collect banking info using a Short Text Entry field, but you also must add a sort agreement and an e-signature widgets  to the form, so your users can  agree to provide their SSN along with personal info.

Adding a License Agreement to a Form

How to Add an E-Signature to Your Form

Without the widgets, your form will be marked as a Phishing form and your account will be suspended. 

We also have eCheck.Net payment integration that will allow you to accept and process payments from bank accounts .

How to integrate eCheck.Net with your form?