Moving from low/mid tier items to higher tier items in the auction house

I've been playing the auction house ever since I found out it's rather easy to find and flip underpriced items in the 100-500k range. I've found out some basic rules that increase my success chance - which have sort of started failing miserably over the last week or two. I've come to the conclusion that for at least the short term, low-mid tier item auctioning is broken and the prices fluctuate all over the place, with seemingly much less number of real buyers. I seriously think there are more people flipping items than actually buying things for using them.

I've kept a spreadsheet and my profits sit at around 7mil after 50 wizard items. I know that's actually pretty sub-par compared to most people who do this but that's beside the point. I'm ready to move out to the actual mid-high tier items (items around 1mil-5mil range and buy them to resell in the GAH?). However, I'm not sure what kind of items or rules I should be looking at.

The problem is, there seems to be a REAL shortage of items in this range -- items that are actually worth that much. I've found maybe one or two to invest in. Are they all being posted over to RMAH? I can SWEAR this market existed (while I was amassing funds to play it)... Is anyone successfully playing the auction house at this range - or is it broken for you guys as well? Please advise.