Help cleaning built up dirt

[FastGunna]

I live on a dirt road in a house that is far from sealed so dust builds up quick. Normally I clean it every 2 weeks which has been working but I missed a cleaning because I was out of air dusters. What I didn't realise is that 3 weeks is all it takes to build up to the point that the dusters just don't cut it.

So first off, I need help getting the built up dirt off, most of it is in non important areas but I'm mostly concerned about the top of the GPU.

Secondly I'm looking for a cheaper alternative to air dusters. I think i saw a refillable one once but haven't been able to find one.

 

[jrlawson]

The only truly safe option is the air duster. While there are other things you could try, I really wouldn't trust anything else.

 

[JamesSneed]

If you build your own, next PC think positive pressure with the intake(s) having filters.

An air compressor works great if you have one although you will certainly want to be outside.
http://www.amazon.com/PORTER-CABLE-PCFP02003-3-5-Gallon-Pancake-Compressor/dp/B00BMUGQNC/ref=lp_552660_1_2?s=power-hand-tools&ie=UTF8&qid=1392690120&sr=1-2

 

[Z-Tech]

I bought one of these and couldn't be happier with it:
http://www.amazon.com/Metro-Vacuum-ED500-500-Watt-Electric/dp/B001J4ZOAW/ref=sr_1_1?s=hi&ie=UTF8&qid=1392690163&sr=1-1
It more than paid for itself by not buying air cans, and its more powerful than cans.

 

[FastGunna]

I actually did build with positive pressure in mind, however I don't have enough + to make up for the hole in the top. I plan on getting an h100i before summer rolls around and that might help (by filling the hole). I'm using a Storm Scout 2 case.

I might be building a PC for my dad in the not so distant future, what would be the best case to keep dirt out for under $70?