what Fi?

Low Fi? Mid Fi? Hi Fi? what seperates each from the other?
These days some companies are making some very "hifi" all in ones, ie Naim
the difference between the "fis" is a matter of opinion.

whatever criterion on proposes is subjective.

it is very difficult to arrive at definitions that are not subject to dispute.

using price is somewhat arbitrary, as is quality because of disagreements as to what constitutes quality.

it is essentially a philosophical question which has no definitive answer.
The entire technology has progressed a long way since the 70's. The terminology is never again going to represent the kind of polar differences we saw back then. It's all "HI-FI" now. Go to Starbuck's and see.