I want to experiment with ND filters and have concluded that I'd prefer a Variable ND rather than fixed ND ones (more versatile etc). For now, I'd get a 72mm one to use with the Sony G 18-105 f/4 PZ lens (my only wide angle capable lens) I don't want to spend a lot of money for now. I've been looking online and prices seem to vary greatly. For example Tiffen, B+W, Hoya, Cokin, Kenko etc are too expensive for me now, Hama, Camdiox and Polaroid are of an average price while Fotga, Vivitar and GB Optics are cheap. Any brands to suggest or to avoid?