I know this is a long read but it will be worth it as noone has mentioned the following:
Remember, pumping out warforged isn't just as easy as that. There are materials required. Stone, iron, dark wood not to mention mithral and adamantine. That means, an average warforged weighing between 272 and 318 pounds would cost in raw materials, whatever their cost price would be. That being said, adamantine (weighing double) or Mithral (weighing half), would also have an effect on the price. (this all depends on the proportion of what each material ect is used to build a warforged but is a good place to start) That price however would be for the body of the warforged only.
The true question arises in giving it sentience. You would indefinitely need to treat it as you're creating sentience similar to creating a homunculi and there would be an exp cost involved. There would then also be additional gold that needs to be spent (as with creating a magic item 25/2 times the exp used). The question that needs to be answered is, how much exp does sentience cost? 100% complete sentience that is 100% independent from yourself as the creator. A homunculus as created by an artificer costs 2000 gold and 160XP yet is always dependent on the master and can only ever have 2hd lower than its master's max. That being said it also can't take class levels nor is it capable of independent reasoning. With this in mind, would it cost 3x more exp to create a sentient being? 5x?
(or would one say that sentience is granted by the creator same/similar to the homunculi? Also how does the character level seeing as a homunculi requires exp cost from his maker. Could one they perhaps say that every level gained after sentience is bestowed upon a new living construct, that the exp cost is paid by the Deieties of eberron? Or even from Siberys, Khyber or Eberron themselves? Is this not perhaps the crux of the Draconic Prophecy itself? That the new race, that never sleeps, rests or ages, taps exp from the original three creators of the realm and that have, in essence the potential to outgrow even the Dragons and eventually ascend to God-hood? )
Another point to consider is the creation forge. How does it work? Without a creation forge, there is no warforged. Is it a structure built and fueled by bound a powerful elemental or elementals? This makes the most sense to me seeing as binding elementals is what fuels eberron from the Lightning Rail of House Orien to the airships of House Lyrandar. The forge would no doubt be an artifact level item but exactly how does it work, what spells, feats, Caster levels are necessary in order for the forge to operate?
Thanks to those dedicated eberron fanatics that were willing to read through my long post