Mark Twain wrote:
As I'm on a very limited budget I'm not going to be
able to invest in such equipment and I have other
items I need to buy first.

Robert

Where the fan blows down onto the heatsink, the
dust will be near the top of the heatsink. A
tissue moistened with a bit of isopropyl might
work, and a pair of precision tweezers for picking
out stuff that doesn't belong. That's better
than nothing.

You can clean it manually, with hand tools,
being careful to not stress the fan hub too much.
I learned my lesson, by ruining the Coolermaster
fan on my current heatsink, and having to
replace it. The screws on mine were relatively
easy to remove, and a standard fan could take
its place. That's a requirement for me when
I buy coolers, is making sure a regular fan
functions as a replacement.

Paul