I should add I was hoping for the design above with the stripe at the neck and hem, not the sleeves and hem, or the colored sweaters of the later films.
I'm leaning towards the Finneas & Co sweaters from Alivan's.
Well, I know you're hoping for the design including the stripe on the neck, but I bought my girlfriend the Slytherin sweater from the Universal store and she absolutely loves it. It's made of high quality lambswool, so not only is it of high quality, it's warm too. All of the designs I've seen that include the neck stripe have all been on the cheaper side.
The ones Universal sells are made by the company that made them for the movie out of the same materials, you really can’t find a better option than those.