I love lawyers who tell people "just say you're not responsible if anything goes wrong, that will remove you from any liability".
I recently stumbled across a product (cleaning soap) that had a giant "THIS PRODUCT IS WHMIS EXEMPT" label slapped across it where a WHMIS label should have been.
Turns out the product contains a suspected carcinogen and a skin irritant, and employees using this product were developing reactions to it.
When questioned, the response from the company rep was "oh well our lawyer told us that because our products are not harmful to the environment we don't have to comply with WHMIS legislation".....
I'm not going to argue law with someone who does it for a living full time, but it's not so easy to waive liability responsibility as just displaying a notice on your website. Disclaimers can't save you from screaming parents on the news at the end of the day....
At the end of the day, putting all the legal aspects aside, there is a moral and ethical responsibility at play here as well. One has to be able to sleep at night.
I think the credit card "membership" idea is a great way to go about it.