My first question would be mountain or road bike, and what kind of fork are you looking ar? Sure, suspension forks don't usually come in a 1" headset size (but they used to). There are plenty of road forks in 1" headset available, so just get the fork that's right for your frame.
If it's a mountain bike and you want to go rigid, check with your LBS to see what they have laying around from other people's upgrades.