Well, you don't really need an Epic item until you've hit the pre-Epic cap.
Two examples:
Need to penetrate DR/Epic? +4 Bane weapon. A +6 weapon costs 720k in enchantments; a +4 Bane weapon costs 50k in enchantments. You can have 14 +4 Bane weapons for the cost of a single +6 weapon. As there's something like 31 different Bane properties (21 if you ignore the Humanoids) you will eventually want to switch out for an Epic weapon.... unless your DM permits the extra +2 Enhancement from the bane property applied to it's target with the Enhancement bonus from Greater Magic Weapon - in which case, 31 +1 Bane weapons to cover the entire spectrum only cost you 248k. Sure, if you need that +8 weapon to increase your chance to hit any, go for it.... but only after you've exhausted non-epic items.
You can have a +6 Peripat of Wisdom and have read a +5 Tome of Understanding at a cost of 173.5k. A +8 Peripat of Wisdom costs 640k. Sure, if you've already read the +5 Tome, and have the +6 Peripat, and you still need a higher Wisdom score, then yes, go for the +8 Peripat (unless your DM permits Epic Spellcasting as written, in which case, even without mitigation cheese, Fortify lasts 20 hours, and a +8 Wisdom Enhancement is DC 31 (with the 24 ranks in spellcraft you'll have at 21st level, DC 31 shouldn't be a problem if you take 10), costing 279k gp, six days, 11.16k xp to develop - compared to a +8 Peripat of Wisdom, which costs 320k gp, 640 days, and 25.6k xp to forge... but doesn't use up one of your Epic spell slots and a minute of your time every day).
However, it does make found Epic items considerably more likely to be kept and used.... assuming they can't be sold, that is.