I like the headphone suggestion, if you don't have a couple pair already.
7506's always are a good pick.
I'd also recommend the Ultrasone HFI-450 at that price point.
I also think checking out a pair of small monitors might be a decent idea, if you don't have more than one pair already.
If you're stuck on a mic, I LOVE the Audio-Technica Pro 44 suggestion - great call, slackstallion!
Here's another to consider: Crown Sound Grabber II PZM Condenser Microphone | GuitarCenter
Maybe call Brad and he can hook you up with two at a discount.
Good luck with your choices.