Benefits:
No large market channel issues, no confusion upon buying and selling ( you know where to go to buy and sell item A-Z). No time zone penalties/advantages.
Easy to implement. Players happy.
Code: (Simple Model)
NPC_AA in map_1 Sells low noobie armours.
NPC_AB in map_1 Sells low noobie weapons.
NPC_AC in map_1 Sells low noobie books/clothes/spells/(basically not armour & weps).
#NOTE: All the NPC's selling these items buy them back @ half(quarter?) price.
NPC_BA in map_2 Sells medium noobie armours.
NPC_BB in map_2 Sells medium noobie weapons.
NPC_BC in map_2 Sells medium noobie books/clothes/spells(basically not armour & weps).
#NOTE: All the NPC's selling these items buy them back @ half(quarter?) price.
and so on..till higher level maps with higher level items/armours/etc.
Optional: Rare drops - any mob can drop them (but less chance if your levels are higher than the mob {to prevent higher lvl's farming low end mobs} you are fighting) - every player has a fair chance to find them. With ingame demand and supply setting their prices. Nothing overpowered.
Now i feel less guilty for that economics test I should be studying for.