The best option, without any doubt, is hunting rope belts in dark cathedral at POH. There are massive amount of dark monks, and rope belts "real" drop rate is few times higher than drop of protective charms. From my experience I can tell You, that knight at lvl 60 (free ACC) with boots of haste and decent sword, can make profit close to 100k per hour.
I think it is possible to start hunt there from level 30-40+. The only issue is to avoid Giant spiders during your way to cathedral, beacuse there are many at POH, and may be deadly for lvl 30.