best phono stage under 10k

Not much of the above is helpful to the OP, I wouldn't think, unless there is some factual information about immunity to RFI.  The fact that a unit is "quiet" in one's own home is not evidence it would be quiet in the OP's high-RFI environment.  But then also, the OP can do a lot to improve isolation by messing around a bit with ancillary items, like cables, AC cords, etc.

I thought the major issue here was eliminating RF from the adjacent radio transmitter.  I am fortunate enough that I have no such problems, living in the industry-less Washington DC area; there are some huge radio and TV station towers in town, but the closest to me is at least 5-6 miles from my house.  Therefore, I have never had to tackle the problem head on. However, I am a very longstanding user of Ralph's MP1.  I love that thing.  Besides thinking about shielding built into the unit of choice, you also want to use shielded phono cables, and since shielding raises cable capacitance and since cables per se are antennae, keep the phono cables and all other cabling as short as possible.  I'd also suggest a phono stage/linestage with a separate outboard power supply, a la the MP1 and others.  Keep in mind the basic fact that tubes are no more likely to bring in RFI than are transistors, and maybe less so because of relatively foreshortened bandwidth, as I mentioned above.  Eliminating RFI is mostly about careful design and build.  If you're in the Herron price range, and if you want balanced (I do), I would also suggest you take a look at the fully balanced Atma-sphere MP3.  It's a candy mint and a breath mint; you won't need a separate linestage.

Tubes are no more susceptible to RFI than solid state.  In fact, to the degree that SS components may operate across a very wide bandwidth, up into the hundreds of thousands of Hz, some SS devices might be worse than a similar tube device.  Immunity to RFI depends upon how and of what material the chassis is constructed, internal layout of parts, length of wires connecting up the circuit inside, and deliberate shielding of any other kind.