I wanted to open your (and hopefully other people's) eyes to a particular vendor item that I've been selling well recently. "Formula: Large Prismatic Shard" http://www.wowhead.com/item=22565/formula-large-prismatic-shard is available from only 3 vendors (Silvermoon, Exodar and Shattrath) and as a limited quantity item, meaning there will only be a maximum of 2 on sale at once for anyone to buy from vendors. This has been selling BRILLIANTLY on the Auction House for me. I know there have been a lot of posts about people detailing complete lists of vendor items to buy, but this has been something special for me.
After parking my primary banker in Exodar to reduce lag issues, I took a run round to the trainers. I found this item at the Enchanting Supplies in Exodar, next to the trainer. It is bought for just over 5g. Having not tried reselling Vendor items before, I put it on the Auction house for 15g to begin with. For every one I sold, I increased the price a little, and have now settled on a "maximum" price of selling this formula for 165g. I tend to put it on for a 48 hour auction with no competition, and within that time it sells.
I have no idea what the attraction of this formula is, I've levelled enchanting to 450 on two seperate characters and had no need for this formula to level. Checking the prices of Large Prismatic shards and Small prismatic shards on my server, I can't see any major profit from learning the formula either. Perhaps it's just enchanters wanting to complete their skillbook, or do you think I'm missing something? Can you or any of your readers enlighten me as to why this is selling so well?!
I think I've made over 1500g from this item already in pure profit. Not bad for 30 seconds of running to and from a vendor for 160g profit each time.