Let me try once more.
First point. The 500mA I suggested was:
1-A guess or vague memory. Don't quote me on it.
2-Referring to the USB specification for the 5v power supply, not the output or available current for things like "phantom power"
3-just because its a specification, doesn't mean everyone follows it exactly.
Second point.While there may be some folks who have trouble with USB bus powered interfaces relevant to phantom power supply, I have seen no evidence it is more than a small minority of users. Yes its a thing. No I don't know how big. It is potentially something to be aware of and consider when shopping.
Yeah, avoiding it will generally involve upgrading from the most economical models of interfaces.
And I would assert that we don't know what percentage of the group of people having such problems can be traced directly to the interface, so its possible even a smaller sampling could be blamed directly on that. Again, I don't know.
But thinking this through- The 5v is supplied, conditioned and regulated by the computers power supply.
Is the power supply up to the task of supporting the processor, hard drive, cooling system, various other processors and cards and all the connected devices? Are some people using economy computers with economy power supplies and expecting too much?
Another example: Would I expect trouble from a laptop, powered from a 19v power supply, stepped down to 5v USB output, powering two keyboards, a Launchpad, an interface etc. and the interface being expected to step up power to 48v for say two mic circuits? Uh, I don't think I'd bother trying it. But yet it might just work!
And another possibility is that some of those peoples issues aren't insufficient power at all, but induced noise. We are after all talking about power sharing the same circuit as the mic signal. But is that noise introduced by the interface, computer power supply, or???
The plot isn't just thick, the recipe is complex.
As to recommending an interface in the desired price range, I have been avoiding a specific recomendation because it would involve the phrase "I've heard"
My personal relevent experience is with an interface that is long out of production and support has been dropped long ago. Yet it still works fine for what I need. I have never used its phantom power because I havent needed to.
But, I would say that based on that experience, If I were to consider replacing it I'd consider another similar Tascam unit. It has worked well. So yeah, the current model USB2X2 or USB4X4 would make my "short list" And FWIW, both have an external power supply/wall wart if I am not mistaken.
(I am looking to instead add something well up the ladder FWIW, so no, I am not shopping for one right now.)
Another point, if buying new- My usual sources have liberal return policies and great sales help. So its like demoing the unit......
And dipping into the "I've heards"
Good sources tell me that while Behringer went through a bad patch, their current stuff is considered pretty good for the price point. And I'd also point out that (I've heard) the M-Box product line had the same reputation under previous ownership and is again considered better now.
Kind of a warning about buying used though I reckon.
And again, if you do end up with an interface that works well otherwise, and the phantom power is an issue, there are pretty affordable stand alone phantom PSU's to consider.
And for some users, portability and USB bus powered are considered attractive features. So there's that......