You will still want the lowest noise power supply, regardless of whether the unit is tube or solid state ... especially with small signal tubes which can be a *very* low noise application.
Although I prefer linear supplies for some applications, I must admit that the switch mode supplies available today and not necessarily designed specifically for audio applications can offer extremely low noise. The key of course is selecting an known good unit.
Perhaps more importantly, though, is that such a well selected switch-mode supply will not have the 60Hz line frequency and it's harmonics (120, 180 Hz etc) as noise, which is something a linear supply can minimize but never eliminate. Especially for small current applications (under 3A and 24V) the options in the market are quite attractive, and offer lower noise than linear alternatives.
If the recommended current is known (it appears it is in your case) then I would not choose a supply that cannot reliably meet that current demand without voltage sag. You can safety use a supply that is capable of higher current (but keep voltage to spec), as it was mentioned by someone here, it will only use the current it actually needs.
Regardless, there is absolutely no justification for the prices quoted in this post. I can see $500 for a retail price for a finished, bricks-and-mortar limited distribution supply unit in a nice retail box. For a direct-to-consumer marketing model, I would expect to see $100~200 less (not including shipping).
I am a DIY'er so I would simply build one, and it would not cost me much more than $100 in parts with nice cosmetics, and quite possibly less. It would not be my first power supply build.