there's a profession achievement which asks your guild to craft 500 epic itmes with an ilvl of at least 476.
In Cata, the cheapest way was crafting alchemist trinkets.
What do you think what is the cheapest epic craftable nowadays?
Gonna breathe some life into this thread as in 5.1 Guild cloaks are transmoggable and I'd really like to get them
As of now it feels like the most efficient way to get this is by crafting Pattern: Spelltwister's Gloves. They require no Spirits and only 4 days worth of dailies. The item is also BoE so it can can be DE'd. You can use the spirits you didn't use crafting the item, make a CD free Imperial silk.
Every other crafted item either requires a daily CD from a separate profession or multiple Spirits to craft.
Only downfall about this is that people will not want to give up their CD if they want to make the bags.