Since you shoot all Nikon you should pick up a Nikon N90s
First and foremost, you are going to be able to use some of your Nikon lenses with that camera, which is awesome. Second, it is all electronic just like your DSLR. It'll be the easiest transition to film that you could make. It has auto focus, auto and manual controls, a digital LCD, etc. Biggest thing is that it's metering is also just like the DSLR. You can throw the N90s on something like aperture priority and you're set. Also, It's pretty rugged, I've shot my friends N90s and it's a solid little camera.
Honestly, I don't know much about Nikon, so you should definitely read this review on it.
It's also in your price range, I honestly think this would be the best fit for you. I have two friends who are shooting their portfolios on this camera and they haven't had an issue yet. So even though you can pick one up for like $65 bucks, it's going to be a workhorse and give you quality images.