Or maybe wand x + wand x = wand x (recharged)? Sort of a minecraft style repair system - put in two almost-spent wands and get back one fully charged one.
How about recharges use something valuable like diamonds and other gemstones? You'd have a few different builds that could pay for that, but you'd need to plan ahead. Alchemy would help to a lesser extent, but Piracy and Perception would be what made them renewable. They would kind of work together in the way Smithing and Tinkering do, sort of.
I actually like this a bunch - because it reduces your total # of burned-out wands available for new wands. Heck, even wandX + burned-out-wand = wandX recharged would be pretty good. Burned-out-wands are the basis for wand crafting, so using one up is a pretty good cost. I can imagine a tough battle where I suddenly need more charges of my wand... but I'm fretting about whether or not I can afford to lose a burned wand...
And here I was thinking that making you less inclined to use the wands you do have because you need to save them for later was part of the problem. It usually leads to eventually selling them because you held on to them so long they lost their value in combat. It would be more interesting to make Wand Lore a skill that lets use use them as your main form of attack, as long as you can fuel them with an external material. Aqua Vitae would be a pretty good one too I think.
I created a mod based on your suggestion. It is here: http://community.gaslampgames.com/threads/wandcraft.3826/ Enjoy and I hope that you like it.
