This isn't true, and should never be given as advice. Wire does one thing - ONE thing only - and that's conduct an AC current.
...
Wires have ZERO audible impact on sound quality, full stop. If you're spending more than about £1/m inc terminations you're spending too much.
In your humble opinion ... right?
Saying
keep wire in proportion to your system cost is meant to restrain people from spending excess money, not to encourage them to spend more.
You are starting an old debate that can not be resolved, and does not serve the goal of helping the original poster.
If you have suggestions for wire, then make them. But this is not the time to start a tired old debate that does nothing but distract from the central purpose, which is to help this person find some reasonable wire with in his budget that satisfies his needs.
Not too long ago, most would have said start at about £2/meter unless you want to buy common twin lead in bulk, that can take you down to about £1/meter.
However, with copper prices rising, the cost of basic wire has gone up, actually a couple of times in very recent history. The wire that used to cost £2/meter now costs +£3.00/meter. And what once cost £1/m now costs about £1.65/m.
The Original poster can spend as much or as little as he wants, but from a practical perspective, depending on his priorities and needs, wire in the £3 to £6 is all and more than he needs. Still, if he chooses, he can spend more, who am I or you to deny him. And who am I or you to deny him if he plans to spend less.
The suggestions I made cover a wide range of quality and prices, certainly the OP can find something in there that meet his needs, or at least suggests something that would lead him to find something to meet his needs.
Personally, I see no point in expensive wire to the surround speakers. There isn't a lot of demand on them, so common twin lead is all you need.
As to the front three (left/center/right) that is up to the individual, if he want slightly better wire there, then that is his right. But I would still suggest he not break the bank on it.
And if you want to council him to not spend a lot on wire, then have at it. But when you start making absolute emphatic statements ending in "full stop" or "period", you are wading into quicksand. No good can come of it, as you have found to your detriment in the past.
So, if you have advise and suggestions on the purchase of wire, please make them. But make them politely. Do not try to dictate truth to the masses no matter how much you believe it, simply make your case and move on.
I stand by what I said.
Steve/bluewizard