The only amp that I'd consider a true "bedroom tube amp" would be
the Peavey JSX Mini Colossal.
http://guitars.musiciansfriend.com/product/Peavey-JSX-Mini-Colossal-Guitar-Amp?sku=480777
It has a single EL84 power tube that you can push hard, thanks to it's built-in power attenuator. The only down side IMO is the 8" speaker. But at bedroom levels, you're not going to be generating any chest-pounding bass even through a 4x12", so the 8" probably won't be much of a drawback in your case. It does have speaker outs so you can buy an extension cab down the road if you ever get a chance to move more air.
They just dropped the price on the Mini Colossal to $300, which really isn't bad. Although it has a tremolo instead of a reverb, which might be a deal breaker for you.
But hell, if I suggested one $300 amp, I might as well suggest another.
The Fender Super Champ XD is probably the best true tube amp in this price range ("true tube amp" meaning it has a tube output section). Or the Vibro-Champ for $200 has a tube output section. Both are good little amps that get a lot of good reviews around these forums.
But both of those Champs are going to present the same problem as any other tube amp in your situation: you need to push the power section into breakup in order to get any benefit from having a tube amp. Pushing the preamp tubes doesn't really sound much different than simply using a solid state preamp. It's the power tubes that make the difference. And if you're not pushing it enough to overdrive the power tubes, then again, you might as well be using a solid-state amp.
The Mini Colossal is the smallest amp that I know of that has a built-in power attenuator, which allows you to push the power tubes as hard as you like but still gives you a chance to bring the volume down before it hits the speaker. It's like a master volume between the amp and the speakers.