My plan for patch 4.2 has worked out pretty well, most of my predictions worked out well though there were a few surprises. I've done over a million gold in sales since the patch dropped (250k in the first 24 hours). That's gross sales, profit is harder to say since I'm always buying stuff too but my liquid gold has gone up by over 500k in spite of dropping close to 200k on BoE epics for my level 85 characters.
As I expected demand was greatest for the first few days and then tailed off. There were a few surprises however. Demand for several items has held better than I expected.
The biggest surprise is how the ore supply has gone down and ore prices have gone up. There seems to be a lot less ore available for sale than before. It's tough finding much Elementium or Obsidium under 50g a stack now and Pyrite is usually 150g+.
Another big surprise was how well and for how long the prices of non red gems have held though they're finally falling and starting to stay low now. Mind you that's probably mostly because I wasn't very aggressive with my undercuts as long as I was selling them in decent numbers and the campers were having trouble finding enough cheap raw gems to stop mine from selling. Now, the campers seem to have stock again so I'm letting them own the market and sell all the gems they want... As long as they're not selling them for more than the raw gems go for. ;)
I was also very surprised to see Heavenly Shards skyrocket to 70G+ though in retrospect I should have realized that would happen in the first place. There aren't very many people running normal or heroic 5 mans where blues drop so the supply is down. Most of the shards available for sale now probably come from crafting and disenchanting PvP shoulders/legs. The cost of mats to make them is up so the price of shards is up too.
Ebonsteel Belt Buckles have been very, very good. After the first day selling huge numbers at or around usual prices the price skyrocketed. Until very recently I had no trouble at all moving 60+ a day for 300-500 each. I'm so glad I had all that Pyrite Ore stockpiled just in case epic gems came out. Buckles were my exit strategy all along but I never expected them to be this good! The campers have been more aggressive the last few days though and prices have dropped under 200g again.
Carnelian are selling north of 30g with multiple buyers spamming trade for them all the time. Demand for Inferno Rubies is finally starting to slow down. Inferno Ruby prices were holding strong on the auction around 120g raw and 140-150g cut but seem to be slowly going down now with several sellers willing to go under 140g the last week or so. Knowing this server and all the constantly undercutting auction campers I figure prices for both will keep going down now in spite of people starting to unlock the pattern vendors increases demand somewhat.
Truegold tanked badly, for a while it was selling around 500g per bar. I've been quietly buying out the cheapest for a couple weeks now because I expect the price will go up as people start unlocking the pattern vendors. In fact Truegold prices started going up yesterday since the local auction bot was spamming trade all day long to buy it. Naturally the first thing I did when i saw that was buy out 9 low priced bars I'd left up earlier so when potential sellers looked at auction prices to determine what to sell to him at they'd see Truegold going for 640g instead of 510g. ;)
Volatiles, especially Earth, Fire and Water sold great until recently. I bought plenty for 10g or less before the patch and sold most of them for 20-30g since. Recently though with all the Firelands dailies the Earth and Fire markets have been flooded. Prices for those are now under 10g each and I'm stockpiling them again. Water is still selling for 20-30g though and I still have plenty to sell. Life and Air are mostly unchanged, respectively around 10g and 20g each.
Overall it was a good run while it lasted but the campers seem to have finally found more stock or adjusted to higher materials costs and are well into the process of killing the goose that laid the golden eggs again.