I have many categories and products in my store, BUT I have this one category of products, which is small parts, and I would like it to go this way with the shipping when someone orders:

customer buys 1 or more items, from this category, shipping charge is always the same, $9. No matter what qty.

Reason is the parts are so small that even if they ordered 1000+ qty they would still likely fit in a USPS flat rate box.

Problem is, I have other products in my store that I DO NOT want to offer flat rate shipping as an option for but when I enable Flat Rate shipping module it becomes availible for ALL items, and not just the category that I want it to be availible for.

How do I correct this?