An indiscreet question: why would you need filters? Aren't your pictures good enough? I think they are! And you seem to know enough Photoshop to get any result you fancy.

Everything you do to your initial capture changes it, but seldom, if ever, for the better.
Filters were great in the old days, when a yellow, orange or red filter could make or break those clouds on your black and white work, or when you needed a neutral grey because your film was too sensitive. Or when you wanted the soft-focus effect only a Dutto filter could give (Dutto's have concentric rings that give a softening effect).
Nowadays, and this is my personal opinion of course, is that only a polariser is worth having.
I may have a cokin one hanging around. If I find it, I'll pm you for your adress. 

There are no Borg. All resistance is fertile.