Tube pre-amps $3500 under to add "warmth"

You can't beat a 300b for warmth.Especially the TJ meshplates.Look for preamps that use the 300b.I own a Supratek Cabernet that uses these tubes but there must be others.

The differing opinions of Mrtennis and Audiofeil make for interesting reading.

Audiofeil,I think you are being a bit harsh.

Many people still want a tube preamp that has that classic tubey sound.Unfortunately this is typically delivered with a loss of performance in other areas[and I have owned and heard many tube preamps like this].So in this regard you are generally correct.
There are tube preamps that sound both modern and tubey though.I own one and have never been more satisfied with any component.It is an absolute keeper.

Mrtennis,
My choice of preamp is the Supratek Cabernet 300b.It has the classic tube "gorgeousness".It is outside your budget however and the new Cabernets use different tubes I believe.Also the cheaper 300b tubes like the EH are not a patch on the mesh plates in this regard.
Mick Maloney from Supratek might be able to make you one especially though.The Supratek Sauvignon is a fantastic preamp but not as "tubey" sounding.It might be able to be tweaked though for a more tubey sound.
Also you should contact Supratek,describe the sound you are wanting and ask Mick if he can make you a preamp with this sound and to your budget.He is a busy man but his aim is to please and might be able to help out.No gaurantees but worth a try.