Well it is and it isn't - one man's midrange is another one's high-end and some manufacturers have 'entry-level' ranges that start in four-figure territory!
So, let's consider the core enthusiasts' market - excluding both the ultra-cheap kit in Woolworths/Argos, plus the astronomically expensive kit that (if you're lucky) one dealer in the UK might stock.
In those terms, you're talking budget kit being the kind that'll make you a sub-£1000 system (even a sub-£500 one). So, that's @£150-£300 per component for amp, player and speakers.
Mid-range will be next-step up kit - components costing £600-£1000 each perhaps, maybe more - with high-end when you're talking four-figures for each component.
But with laptop + DAC + active speakers, plus AV-based systems, now in the mix, such traditional hi-fi maths isn't the only way to go. (And that's before you've added a turntable. Or an iPod dock. Or a TV!)
It's not a precise science, as you can see. It's far more important for you to see and hear products at a range of price points and experience how YOU think they perform for the money, rather than worry about largely meaningless catagorisations.