One big ticket enchant I list frequently, is mongoose enchant scrolls.
If you have this enchant, on my server you can purchase the mats on the ah, place it on a scroll and profit about 100g. Since scrolls have no listing fee, you can relist it and not loose money.
I find these sell better on weekends. It is also a good idea to list them in sets of 2 or more. (They sell in sets quite frequently)
Some tips to consider:
DE’ing Netherweave belts can get you a lot of the mats you need for these enchants
You can turn Void crystals into prismatic shards.
You can turn nexus crystals into small prismatic shards.
Look for lesser and greater planar essences, there might be a price difference.