Budget Tube Amp (newbie)

Old iron IS better than new iron.

Not that it specs better or anything like that, you just can get old iron for a lot less than new iron and almost without exception transformers are well made. That's the most expensive part of an amp and manufacturers pretty much always made sure that if they were going to tool up a transformer, they did it right. Yes, good design is good design and transformer design has been optimized for years.
For what it's worth, Quad II sounds much better than Citation II.I have three Citation II here right now and that pentode input stage is for the birds. The Citation transformers though are sublime. Properly rebuilt they are a revelation. Bruce Moore for instance gutted many a Citation II with just that in mind.
Yes, tube rolling, just like cable rolling or fuse rolling is basically an exercise in the imaginary side of the hobby...

Lots of good advice here. Try to learn from it. In tube sound, the warmth you like is supplied most by a tube preamp. So you could get a tube preamp  into Solid state amp (there are a lot of them, used available) I’d think of some of the Pass designs like the Adcom 555. I started into the ‘tube’ sound with a used Audible Illusions PreAmp, still made new and with many used ones available in your budget range.

Old iron IS better than new iron.

Old iron is frequently cheaper than new iron.

Quad II sounds much better than Citation II

I never thought so, but I don’t like Welch’s & ethanol either. IMO, the CII is more coherent from the low mids on down while the QII were somewhat confused in the systems in which I heard them.

In tube sound, the warmth you like is supplied most by a tube preamp.

No it’s not. In all cases, the entire system contributes to the final sound. A nice tube preamp is not going to help a system with a Zippo 250 SS amp and EarBleed speakers wired with HFXtreme cables. A tube amp may be more/less intolerant of cable/LS.

Systems are built with ’recipes’, all little of this, all little of that to achieve a good balance and just like pudding is all in the eating, amps are all in the hearing.

I greatly prefer a good single malt, hopefully an isle of Islay, to Welch's and ethanol.
At least I think I do.

I've never tried the latter.

We definitely agree on the Islay.
Best I ever had was a 30 year old Ardbeg distilled in 1972.