So everytime I pick up a new weapon the upgrades are available. I've had the katana from the start and upgrades are 'not available'?

When do then unlock? I am playing this slow. only in chapter 5.

The katana upgrades are linked to the story & you'll get them automatically as you progress through the game.

Thanks for that. One more question, if tied to story do they cost $? Just wondering if I should be saving my coin.

No, they cost nothing so you can safely spend the money on other upgrades