Dave Ladely:
I really don't know why so few even seem to know what a capacitor really is, but are willing to spend a lot of money on what is an extremely high profit item, since a cap is a very simple, cheap thing to make. These are all electrolytic capacitors and price does not necessarily mean proportional quality, but does mean proportional marketing and hype to get your money.
Whatever the subjective opinions, a capacitor is really an "instant" battery that discharges all its power in less than a second. That is, it stores electrons and lets them loose almost instantly, and they are gone in less than a second and must then be replaced. Power sagging in an amplifier, if noticable, lasts a lot longer than the time it takes for a cap to discharge. Read a technical description of some depth, then decide.