https://spree-save.herokuapp.com/
During user signup, if you are uncomfortable entering your own personal banking information, select a bank and enter the user id : "#BANK_DEMO" with any password. This will set up a mock bank account for you with fake transactions so you can use the app. $50.00 will also be added to your account so you can go use the app to explore events and purchase tickets.
Passwords are hashed and the app does not save any financial information about the user other than what bank the user uses. Plaid (https://plaid.com) is a 3rd party API that handles all the bank transactions. Paid handles bank transactions fora number of commercial app such as Mint, Robinhood, etc.