They can fund their payment from their bank account through Paypal however it sounds as if they would prefer to pay by bank deposit, not wise for them but fine for you as they will have no buyer protection and it won't cost you a fee. If that is what they want then just send them the name of your bank, the name on your account, your bsb and yor account number. This is absolutely safe, all they can do with that information is pay money into your account.