This is not a quick blast of compressed air. The PC is stripped down, fans removed & cleaned, Case cleaned, CPU re-pasted with performance Thermal Paste and reassembled.
The cost is simply down to chargable time taken to do the clean. Obviously this will vary depending on the case, number of fans, type of cooling and the dirt build-up and type (dusty PCs from heavy smokers tend to be the worst).
To try and give some rough indication:
This PC is a basic build type and had “good” dust. The cleaning time was 1 hour.
This PC came from a heavy smoker. The tobacco tar makes everything sticky and glues the dust on. Everything needs cleaned three times to get anywhere near clean. In this particular case I capped the labour costs at 3 hours.
This however was the finished result:
