There are electric dusters, but they are still costly. Otherwise you could go a full on air compressor, but then you require moisture separators and they still will cost more than you likely want to spend.
There is one alternative though that it seems many people overlook.
Alternative to Compressed Air For Dusting
After a bit of experimentation I found a much cheaper tool is almost just as good as compressed air for removing dust from your pc.
An electric air pump does a pretty good job, and will save you cash in the long run!
Our Recommended Electric Air Pump For Dusting
So obviously, the more powerful the electric air pump, the better a duster it will be. My experience is that even the cheapest ones will do the job, but you will probably want to spend just a little more and get something that has a bit of power behind it.
Our recommended electric air pump is the Intex Quick Fill Electric Air pump, it is available from Amazon and it comes with all the nozzles and adapters you will need.