Here's a little news blurb & interview about the establishment of the Gibson Qingdao plant.
If the Slash model is indeed made there, which wouldn't be a surprise, that still wouldn't explain the higher cost. Better pickups and a little different manufacturing process to accomodate the longer neck tenon help explain it, but not totally.
I'd bet the bulk of the price difference is due to at least one of these things:
It's Slash, so it's more expensive than a standard LP w/maple top (check)
They may use better woods, with thicker maple tops, to meet more strict spec requirements (this is one area where Epiphone is notorious for product variance, at least in their standard production lineup...with a LP Standard Plus Top you may have a mahogony back with maple cap and flamed maple veneer on one guitar, while on another the cap is alder with a flamed maple veneer. It all depends on what was available on that day).
Putting on my tin foil hat - There may have been a screwup along the lines that caused the aforementioned disappearance/delay, and they may be trying to rocover from unforeseen product and/or labor costs, be it from a move in production location or a widespread factory defect.