I've just this morning taken delivery of 1.25" and 2" OIII Lumicon filters from EyepiecesEtc.com. With the Brisbane weather looking like being wet until Easter I won't be able to give an opinion for a while yet, but they've had good reviews.
DGM Optics do a NPB filter which picks up OIII as well as Ha and Hb - it's a great filter which I use quite a lot. Tends to give a more orange rather than green cast to the view, which I prefer over the green of a straight OIII.
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