The "10 years per caster level" is reminiscent of
resurrection. Although if the parallel were exact you would need diamond dust, wouldn't you? And the xp cost is paid by the caster, not the subject. Which is good, since most items don't earn experience points.

Or perhaps it is like
true resurrection (no xp cost) but the cost in diamond dust is paid with xp instead. Although 1000 xp is normally equivalent to 5000 gp (like
raise dead), not 25,000 gp (like
true resurrection).
I take it the items have to be whole? Not destroyed by hitting a black pudding or rust monster, not sundered, just demagicked in some way. In which case it's like a version of
raise dead that doesn't work on people killed by hit point damage, but *only* by death magic. A mass version. Without diamond dust (or with a substitute of xp for gp). Which is kinda cool, although I don't know what level I would assign to such a spell.
Were you making any conscious analogies with life-restoring magic when you created this spell?
[edit] Using my [life] seed and assuming that equipment is 1/3 the ECL of a character, I've calculated that your spell could restore up to 1.4 million gp in equipment that had been demagicked. Although really I would either reduce the temporal range (if you want to counteract a
disjunction that had just been cast on you) or increase the casting time (if you wanted to restore items that had been disjoined years before). Increasing the casting time to an hour (or reducing the temporal range to 3 months or so) would boost the effect to 2.2 million gp restored. That or you could restore items that had been destroyed by any means, but only 1.4 million gp worth.
A 7th level range touch spell could resurrect one item of up to 1 million gp value. With the same kind of modifications; shorter range or longer casting time = more value or can restore any destroyed item, not just one that was demagicked.
That's using my [life] seed, which prompted Sep to say "You're having one of your more eccentric moments, aren't you? " So it might not be entirely reliable.
(Actually, that's a funny line. I think I'm going to sig it.)