My husband and I have Lucius and Bellatrix costumes and the wigs had to be custom cut and styled. Especially Bellatrix because she has gray streaks in her hair. You likely won't find anything accurate right off the shelf.
Hi, the cardigan Neville wears throughout DH2 is actually off the hanger from River Island, its thier aztec cardigan, winter 2009 season so its no longer stocked or even made. But if you search for aztec or even Fair Isle cardigan's you might find something similar or if you know someone who knits you might be able to find a replica pattern online.