Hiding Products that Are No Longer Available

I am constantly amazed at the number of people that continue to order products that I have clearly marked as "SOLD OUT" or "UNAVAILABLE" on our online form. We can't quite monitor inventory levels to use that functionality, so here's what I tried to do.

On the product fields I wanted to hide I started using the "Enable Conditional Logic" field to hide that field based on the value of a hidden field that had a checkbox marked as "Yes". The hidden field was a simple, "hide fields that are sold-out or unavailable".

I could never get it to work. Not sure what I'm doing wrong. What do I need to do to get some assistance?

Not using CSS. Just trying to use the exposed, basic functions of the fields within Gravity Forms. http://www.simpsonfamilyfarm.com/home-delivery/online-order-form/

basic functions of the forms means the features like conditional logic and tying actions of one field into another. I intentionally disabled the qty fields on the products that were sold out, but what's weird is we had a lady submit an order today. She didn't select ANY of the sold out items, but all of them automatically got included in her order for some reason? Does that make sense?

I guess the simplest solution would be a checkbox on each field to make the field invisible briefly as long as it was needed.