Lactose, mannitol, thiamine, Dormin and/or quinine. Instant coffee is used sometimes for tar/mud/brown heroin, not sure if that's a good idea though. Blend it thoroughly to prevent hotspots.
Keep it pure. Sell it for more, sell less for the same. Warn them that it's some strong shit. If it's as good as you claim it will not be considered a ripoff. The phone will probably be ringing off the hook.
In before close.