You can also buy things that some lower levels don't have access to yet like certain crafting items from higher level areas, buy low sell high. But if its anything like my server, once the bulk of players catch up, the prices drop quite quickly. I've found items like gysahl greens always seem to sell at a higher rate on the market, p!us once you unlock beast tribe quests, even the neutral venders sell some crafting items that go for a good price