Those magic items are legit enough… and there's more
Both the quiver of Anariel (Lone Drow Web column "Companions of the Hall") (28,000+ gp; 1 lb.) and the quiver of plenty (Dragon Compenidum Volume 1 139) (18,000 gp; 1 lb.) are overpriced compared to the quiver of lies (Book of Vile Darkness 116) (12,000 gp; 0 lbs.) if all the wearer needs are standard arrows and the wearer never plans to upgrade.
All three items have issues: the Anariel having appeared on Wizards of the Coast's sister site to promote material from Mirrorstone, its juvenile publishing imprint; the plenty first appearing in Dragon then in a Paizo-published but Wizards of the Coast approved text; and the lies never having been updated for the 3.5 revision. Nonetheless, as these are—so far as I'm aware—the only D&D 3.5e bottomless quivers, they're to what a D&D 3.5e DM is supposed to compare a new bottomless quiver to when a PC sets out to design a similar original magic item.
On the campaign value of endless arrows
I suspect having endless arrows from a quiver is usually less expensive than the weapon special ability endless ammunition because the weapon special ability endless ammunition means not needing a quiver at all. In some campaigns the difference between an archer needing to scour the enemy stronghold to recover only his +1 endless ammunition mighty (+5 Str bonus) composite longbow (16,900 gp; 3 lbs.) instead of both his +1 mighty (+5 Str bonus) composite bow (2,900 gp; 0 lbs.) and his quiver of lies is totally worth that extra 2,000 gp. That extra 2,000 gp also means only having to worry about protecting the magic bow rather than the magic bow and magic quiver—getting the magic bow made of the strongest material so as to avoid it being sundered is likely less expensive than getting both bow and quiver made of that same material… and, if the archer does not protect his quiver, some smart enemy's gonna come along and sunder that magic quiver precisely because the archer has not protected it!
(I ran a campaign where one of the PCs was a dedicated archer, and I explained well beforehand that as the PC advanced in levels and his reputation grew, he'd need to be more and more careful of enemies sundering his bow and quiver. The player appreciated my heads-up and had his PC protect the crap out of his bow and had his PC tote several mundane quivers. When enemies did finally start making sunder attempts against the PC's bow, the PC was ready—the bow was magically reinforced and the PC had a backup bow just in case. Ask if that's a thing, too, in your GM's campaign. If the GM will never sunder or scatter your stuff—and, seriously, some GM's just don't—, this is far less of a concern.)
Consider instead a haversack full of arrows
What an archer really needs to weigh these oodles-of-arrows options against, though, is a handy haversack (2,000 gp; 5 lbs.) and 60 gp for eight hundred arrows. This supply—plus however many arrows the GM lets the archer tote on his body—means even the most profligate of volley archers will have enough arrows to last at least a level or two. (An archer that uses an impressive and absurd 40 arrows per encounter still typically only needs 520 arrows per character level in D&D 3.5e, for example.) Seriously, for the price of a quiver of lies, an archer can buy five haversacks of arrows—that is, without needing to resupply, enough for seven levels of continuous volley fire as described above—and have cash remaining.
Seriously, by comparison, a haversack full of arrows—that are kept securely in their quivers or wrapped in blankets so as not to pierce accidentally the haversack—makes both a bottomless quiver and the weapon special ability endless ammunition an extravagance likely reserved for high-level characters.
