Are you looking for HO Flextrack? The most popular is manufactured by Atlas and short of a 5 pack here and there I bet you can't find any. Back in april 2012 on the Atlas website forums the notion was spread that there would be a disruption in supply. That disruption has turned into an outright shortage.
I was told by a local supplier that the story on the track shortage has to do with moving product lines from one mfg plant in china to another. I know from experience in my industry that such a thing takes a lot of time. The new china plant will make run after run of bad product before getting it right. I am not sure if the track has hit the water yet on its way to us but Atlas tells my supplier that they will have it before the years end. Their website says they were do in a container the begging of November 2012.
I find it interesting that right after the mention of the track shortage Atlas decided to put an end to their Forums on their website. They are there in archive mode only, you can't add anymore posts. Yes forums are expensive to run but did they just want to avoid all the negative messages about their own products not being available?
The scoop I heard was that when the plants in china were being realigned Atlas got left out. Someone was not paying attention to what was happening. This is what disrupted their supply chain. Hopefully they have everything worked out...Cause I love using their track!
ps as of the end of Dec 2012 I hear they got in some track...but that most of it sold right out...good luck..I got mine!