If you have 15 devices that want to control. harmony one is a good choice which it is selling $!!)) in wanchai computer centre, if you have just 6 devices for control, logitech harmony 650 is a good choice for you. It is just around $4xx. I am also using it. Dont suggest to buy those 2nd hand logitech remote from Taoboa as I also ordered one bfr and it had problem after several mth using. For controlling NOW or Cable, you can use the "self-learn" function if you cant find the device from the logitech database.
Don't buy the cheap model from harmony. Slow response and the width of the infrared is very narrow (same experience as you may have some cheap china product come with the factory remote, it looks ok but when you use it you find it is not functioning as good. I always "learn" them to my harmony 880 and it works much better)
Re buying from taobao, I have been using the "2nd hand" harmony 880 for 2 years and didn't find any problem (I frd got another for more than 1 year and happy)