Combining magic items
Devlin's ring and the quiver of Anariel can be combined into a lone magic ring using the Magic Item Compendium rules on Improving Magic Items:
In most cases, if the item is one that occupies a body slot, the cost of adding any additional ability to that item is 1-1/2 times the value of the added power (or the value of the added power plus 1/2 the value of the existing item, if the added power normally costs more than the existing item). (233)
Since the added power of the quiver of Anariel is more expensive than Devlin's ring, the Magic Item Compendium wants you to buy the equivalent of a quiver of Anariel and add +6,000 gp to the quiver's price to have the quiver's effect shoved into Devlin's ring, making it a a Devlin's ring quiver of Anariel or something.
The only reason to do that is if you think wearing a quiver is uncool.
Breaking down the quiver
The basic quiver of Anariel's costs 28,000 gp and added to that is twice the cost of the a standard magic weapon, like this:
+1 4,000 gp
+2 16,000 gp
+3 36,000 gp
+4 64,000 gp
+5 100,000 gp
+6 144,000 gp
+7 196,000 gp
Not including the 28,000 gp for the basic quiver. Officially,
the item only goes up to a +5 enhancement bonus, but the item
scales consistently, so additional +s are included for
comparison. At +8 or more the item is an epic magic item.
And, while 28,000 gp for unlimited typical arrows is exorbitant, doubling the price of a standard magic weapon's cost to have all the magic arrows you'll ever need isn't. Really, an archer specializing in firing volleys can, in a handful of full attacks, easily go through 50 arrows. (Using the core rules alone, an archer with a +16 base attack bonus, the feat Rapid Shot, and a haste effect makes 6 attacks during a full attack, for example, before being polymorphed into a xill.) Such an archer that's buying magic arrows individually instead of relying on such a quiver will, after all, need to buy more than two batches of fifty during his career.
In other words, I know you're angling for magic arrows on the cheap, but this is on the cheap: buying a batch of 100 magic arrows and getting instead nigh-infinite magic arrows is a good deal, especially in a long-running campaign and if using an awesome bow. This DM really does see this as a fair price and would let Devlin's ring produce magic arrows for the costs listed in the chart plus the 4,000 gp cost of Devlin's ring. Ignoring the third-party Devlin's ring, this DM would allow a pair of magic gloves or a magic belt or similar magic item that occupies a body slot to produce nigh-infinite typical arrows like the quiver for but 14,000 gp—half the quiver's base price—and allow enhancement bonuses to be added (and not halved) to that item's arrows using the above chart.
There are a few other ways have a lot of mundane and magic arrows without worrying excessively about running low.
A wand of greater magic weapon [trans] (PH 251-2) (3rd-level spell at caster level 20) (900 gp/charge; 0 lbs.), at about 1/3 the price of the most expensive quiver of Anariel, transforms 50 arrows into 50 +5 arrows for 20 hours by expending one charge. While 50 or 100 arrows isn't enough, 2,500 arrows just might be. Then spend some of that saved cash on an extradimensional space filled with mundane arrows. (Note: The spell greater magic weapon is on a lot of class's spell lists but not the ranger's, an incredibly frustrating and sad omission.)
The quiver of lies (Book of Vile Darkness 116) (12,000 gp; 0 lbs.) isn't a quiver at all but a (maybe slotless?) bracelet that creates a typical arrow or bolt with a duration of 10 rounds when the wearer needs one, just like drawing ammunition.
This may be the most official equivalent to Devlin's ring, which was originally from the Book of Eldritch Might III: The Nexus (2003), published a year after the Book of Vile Darkness. We'll likely never know, but a reader might infer that Monte Cook—author of both Book and Nexus—either changed his mind about the price of infinite arrows, reducing the cost of the later item to 1/3 of the earlier's price, or he believed that the arrows' continued existence past the time of their creation (and all of the shenanigans one can pull with that) multiplied the cost of the earlier item by 3 or he forgot he already concocted an item of infinite arrows and priced the new one differently or something else entirely. Pick a reason or make up your own, but 12,000 gp seems to be the official going rate for nigh-infinite arrows.
The raptor arrow (Magic Item Compendium 56) (6,006 gp; 0 lbs.), while a relic and therefore difficult for some to use, returns—harmlessly, fortunately—to its firer on the round after it's fired so that, while expensive, an archer only needs enough raptor arrows to make one full attack.
The quiver of plenty (Dragon Compendium Volume 1 (2005) 139) (18,000 gp; 1 lb.) produces nigh-infinite cold iron, masterwork, and silver arrows and up to 5 adamantine arrows per day, all lasting only long enough to be launched and deal damage. If the DM allows this and the quiver of lies in the campaign, pay the extra gp for this.
This DM would then allow the player to apply to the quiver of lies or plenty the same kinds of enhancement bonuses available to the quiver of Anariel, but note that, so far as I'm aware, the quiver of Anariel is deeply obscure, present not in a Dragon magazine but only on that now-only-archived Web page with similar pages containing such gems as Raistlin's frog. (Tip: Buy. Them. All.) In other words, perhaps the quiver of Anariel isn't the most reliable source for pricing nigh-infinite magic arrows, but I'm unaware of a more official alternative.