My response continues... "Here's the thing, Fred.
Compressing any gas will enable the intake, by the compressor, of air borne contamination. Whether that contaminant gets by the intake filter of the air compressor, or is a result of the wear of components that are actually doing the compressing, crud gets into the gas stream.
There are many pages on this website detailing how compressed air is to be treated to remove impurities and water, along with water vapor, from the air stream.
In your case you can certainly add enough compressed air treatment equipment to your air line that will ensure that you are not blowing water, water vapor or impurities onto the equipment you are trying to clean with your compressed air.
So, again, I am totally in favor of you taking your route with an air compressor to blow off electrical parts instead of using compressed air gas cans. You can parlay an initial higher up-front cost into long term savings and energy / resources.
The first thing I would do is select a small, oil-free air compressor. That will eliminate the potential of lubricating oil getting into the air stream, and possibly blowing onto your equipment.
That should mean that you will need only to deal with airborne dust and moisture.
You can acquire an in-line desiccant air dryer that will remove ALL traces of moisture from the compressed air. Since these filters might impart desiccant dust to the air, I would follow that dryer with a general purpose air filter, and that to be followed by a coalescent air filter, which will ensure that the air coming out of your blow gun is dust, water, and water vapor, oil and oil vapor free.
Based on what you are blowing off, and assuming you don't want to use your compressor for any other application, I suspect you can get the compressor, air line, fittings, dryer and filters for well under $500. Given the relatively light usage of the compressor it should give you both financial and energy savings for years to come."