I have an old kifaru bag in that range I think. Maybe a bit larger. I’m not sure what it’s called. But I’d pass it on for $100. Pic below…I know it is a terrible picture but it’s all I have of it. I have no clue what model or make it is. It’s old. Like Patrick Smith days. Kryptek highlander pattern.
I have a nomade 2 I'm going to be listing with a grab it in that price range. You could pick up a camp bag or a dry bag to get to the cubic inch size you are looking for.