Can anyone recommend a great tube preamp that also has a headphone out?

I also like the Linear Tube Audio recommendation, but I'd also first check with Don Sachs to see what it would cost to add a headphone out to his SP14 preamp (or just call him to see what he says).  I'd be pretty surprised if he couldn't meet your specs at or below your price target.  Personally, that's what I'd do and never look back.  I'm buying his preamp as soon as I get spousal approval.  Best of luck in your search. 

+1 on the Rogue RP-5.  I have the RP-1 and really like it and the support has been good as well.

I've had a Manley 300 for a few years.  If your budget can handle it, it's a fine preamp. I just made my first audio purchase since the Manley and I'm pairing the Manley with nat mono blocks.  Like them together very much.  I looked at linear tube audio also. Also a strong contender.

@soix 

I agree with the Don Sachs Preamp. I hope to get one soon as well. But HOW does one get "spousal approval"?. I'm not sure my wife has ever given approval....at least until after she hears it. I had to sneak a ScoutMaster turntable in the house. She didn't notice cause it looked similar to the one it reeplaced. But I messed up a month later when I brought her the credit card bill with it listed. I didn't mean to do that.. That was about 10 yrs ago. Shes still with me....43 yrs this yr.