I get the feeling the level of gear you're looking at is below 60. The article is mostly directed to northrend-quality greens (level 68 and up). For players between level 58-70, the quest rewards in outlands and northrend are plentiful and do nicely for leveling. Most greens from these zones only sell to the enchanting market or the occasional twink picking up a 59 piece of gear. For azeroth leveling, quest rewards are a lot harder to come by and underpowered compared to BOE greens. However it's probably not enchanters buying up the expensive ones on your server. The demand for mid-level enchanting mats is sparse and largely only used by people leveling their enchanting. Items with desirable stats are sold for a high price because of their stats and the relatively scarcity of supply. Most servers (excepting new ones) don't have a lot of people killing the mobs that drop stuff in that level range. There's a fairly limited supply of leveling greens, thus high prices for ones than have desirable stats. Has nothing to do with enchanters.