I was wondering if there is any other addon out there that will scan the AH, decide what a good undercutting price is, and then post what I have with one click of a buttons?
Auctioneer was broken by unannounced changes on the 4.3 live patch which had not previously appeared on the PTR.
There is a Beta version available for download, but due to being a Beta rather than Release flagged version it will not appear by default on the Curse Client, nor on their website.
I have had no problems with this version myself however.
I downloaded manually, so can't comment on whether this will work or not through the client but I will include instructions for both methods regardless.
First Method - Set Beta Release type on Curse Client.
If you are using the Curse Client then for an individual addon then you can set it to use a Beta or Alpha release should one be available.
However they are not shown by default due to often being considered test or in-progress versions so bear that in mind.
Launch the Curse Client and right-click on Auctioneer - Preferred Release Type - Beta.
If the client then detects an update it did not previously, then you should be able to update to the fixed version without the need to do so manually.
Second Method - Manual Download.
The Beta, or as the Developer calls it, a Preview Version can be downloaded manually from the developers website from HERE.
Select the Auctioneer or Auctioneer Suite as applicable to your needs.