As far as I know, they are only released at holiday time. The Nordstrom set is the only exception to this that I can recall.
As far as the quality goes, i think they are fantastic for the money. Some are a little more stiff than the regular brushes, but still far superior to most other brushes you could get for the same amount of money. I have many of the reg. brushes and several of the SE sets. I can't tell the difference in the application. The only one I have had any issues with is the 129 brush. It got really frayed and lost shape faster than the others, but I did get about 2 years use out of it before that happened. I can live with that!