I don't have the book in front of me, but I remember reviewing the section mentioned earlier in Unearthed Arcana and I'm "Pretty Sure," that those rules did not apply to recharging magic items, such as refilling a wand or staff with that has half its full charges. My memory however is not reliable by any stretch though. I would check the book yourself to confirm.
According to Magic Item Compendiu and DMG, recharging items are expressly forbidden. This rule is wildly stupid, and I see no logical reason for it. I believe it involves WoTC's violently failed attempt to "Balance," magic items by tacking price tags to it--such as saying a level X character should only have X gold worth of gear, then pricing useless or weak items in the tens of thousands (which they finally ponied up and admited doesn't work...that dreadful concept will disappear in 4.0).
However, most DM's I know that have any stretch of common sense allows recharging items. Your character's long term cost will be the same if he uses, say, wands frequently, and will only avoid the chump change costs of actually carving a staff or wand, etc.
Talk to your DM. I'm sure he'll allow it. By simply pricing the cost to make the item (minus the cost of the non magical materials materials, which I think is 300g off the top of my head for a staff, and nothing for a wand), and divide it by 50, then multiply that number by the number of charges need to make it full.
Storme