I don't understand the question. Antenna VSWR doesn't change from
microwatts to megawatts (with the possible second order effect of the
megawatts heating the elements to the point that they expand in diameter and
length).

Well, if you don't understand the question it is only because I don't
understand enough to ask an intelligent question. When I look in the
HRO catalog may of the SWR meter ads have multiple power settings
(15/150/1.5KW). I assume that you simply select the appriate range
that is just greater than your rig. I was just wondering why the
range mattered. Why not just use the highest power range if the
sensitvity doesn't vary significantly with power.

Even if they cost the same, I'd rather build a nice kit than buy one.
I'd like to understand more about how they work and there is nothing
like getting your hands dirty to understand something.

Carl