i really suggest u to make freya...
its newer, attribute system is "fixed", new armor,wep and so on... its just way better then epi :-X
and as Finito said just make the lower items way cheaper then normal ones... also u can make that u have different enchant chance for those items like for dyn its 90% for vesper 75% (and if u use freya, then 65%)
about codex i would make them solo farm able... about mastery the first step is to make a restriction so max skill enchant is lets say +20 and make the mastery hard to get and ofc delete them from hero reward, since there are 99% only feeders ;)
there are a lot more things u can do to make it more fun for each guys also for the lazy ones and the farmer...