It's not a bug. The search is working exactly as they intended.
As Brian mentioned, it is due to the way their search algorithm was implemented. The pseudo code for it would be akin to something along the lines of (example shown sorted high to low):
low: 0, high: 175mil
display page of 5 items, in descending order of prices
repeat 11 more times
get price from page 12, item 5
new low: 0, new high: price from page 12, item 5
display page of 5 items in descending order
repeat 11 more times
etc.
The system isn't truly able to keep track of which page you last visited and are currently on while browsing the search results. Instead, all it’s doing is resetting the max or min price (whichever way you have it set), and then simply creates a new search with those caps. So if the 5th item on page 12 price was 1,000,000gold, all it’s doing is creating a brand new search with your min/max at 1mil. As you noticed, the items on pages 8-12(for example) could all be priced at 1mil, so it's really just bringing you to page 8 and starting from there, hence the repetition.
If you’re doing a search on every item for sale on a vendor in game -- in order to get rid of the repetition and keep track of which page you’re on, the search would have to query and load the entire database before hand which can be very taxing on the system with simultaneous people searching. Currently, they only have to query the database for 12x5=60 items at a time, which as you can image is much faster than tens of thousands, possibly millions of results.
It must be something I am doing somehow. I'll keep playing around with it. It will probably end in a self face palm. lol
