Mr Pig, you could settle this argument by asking someone to randomly swap a few things around and lisen blindfolded. I have a nice stand because it looks nice, for which I paid too much really. I can't tell the difference between it and a stack of telephone directories sonically, even in a good acoustic environment, like a radio studio. Doesn't mean you can't of course.
If all the reasonings commonly given are true of course, then the ultimate hi-fi stand is a Tescos baking tray (£1.99) filled with water and your equipment carefully floated on a block of wood.
If I had known before I probably wouldn't have bought my set-up at least unitl I can afford a house with a dedicated listening room/cinema room. For most people in normally sized houses used as a home, then diminshing returns set in incredibly rapidly when stepping up from mid-range seperates.
One think I bought from maplins was mains conditioner, £ 70 so not huge money and I am convinced it did improve the bass. Can't recall if I did a comparison with/without so it may be a case of I spent X more puounds there fore it myst be better, but one thing for sure, it did reduce the mains hum from my amps (this is hum from the boxers themselves - transfomrer noise? as opposed to any hum on the audio path).
You might get the same effect by moving noisey items (electrically) like the fridge and flourescent lighting and switch-mode power supplies to a different circuit breaker. Some older mobile phone chargers and cheap PC power supplies were terrible for this.