Yep, they sure do have them for 10gallons!
If you have a Petsmart near you, you can get one there...
tada.... 10gal divider in action
the bright neon aqua colored part is a bit of an eyesore, but it's a decent divider.
If you want to go cheaper though, you could try getting a plastic sheet of that mesh stuff you can get in hobby sections. It's cheap, has larger holes than the one you can get at petsmart so there's more water flow... and yeah.. only thing you'd have to figure out is how to keep it in place which I'm sure is covered in the DIY section