This question was asked in the past

I would like to know if it would be possible to disable certain payment methods for certain product categories. For example, if a customer has an ipod in their cart, they must only be able to use COD as a payment method, and not credit card.

Would something like this be at all possible?

nopTools Payment Director

I've just blogged about your scenario If certain product is in cart, then only allow COD payment method

Here are some other samples