What is the best cleaning method that has worked for you when cleaning the inside of your computer?

I've heard that compressed air is the best way to get into the nook and crannies by way of ridding out dust between those tight spaces, but the price of a 300gram can for compressed air ain't exactly cheap either.

Two days ago, I instead opted using a blow vac to clean the inside of my computer case. Em dust particles flew left right and centre as little cluster balls of dust. Yet the blow vac did such a good job, I have never seen the internal parts of my power supply before until now. I'm more than tempted than ever to try it on my Mums computer but with a more powerful one to see similar result.