for a start, before so readily spending money, how about finding out the source of the hum.
those noise supressor will cover up/gate it within the setting as set by user whatever noise/hum when you are not playing the instrument. And when you are playing, heh, the noise hum is still present, but just that with the playing, most likely our mind wont register it in unison with whatever sound we are getting from the guitar
anyway, source of hum ranges from cable of amp(2 pin or 3 pin) to wiring/grounding of geetar, radio frequency interference(RFI) to external factor such as close proximity to crt monitor, power source, neon light and so on.
To utilised the noise supressor fully, theres a need to address the source of the hum and if able to minimise/rid of the hum(through knowing where the hum comes from) , using of the noise supressor wth gentle setting will ensure that your signal wont be affected too much. A noise supressor with extreme setting will affect your normal signal while doing its job of "covering up" the noise(yes its covering up actually, not getting rid of the noise/hum)