You could try, but it would be hard. You need some way to get the HDD in and out, and once it is appart, you need to get the lid out to cut... all the while making sure no dust gets in there.
In clean rooms, they keep the room at positive pressure (higher than the outside) so that when the doors are opend, all the air goes out, not in, which stops dust getting inside. You would need something like this, and also a very good quality filter to remove any dust that is in the air in there. The filter alone will run you more than $100.
The other problem is getting ppl to trust that it works. Will you give a warrenty or something? what if the drive breaks 2 months later?
I think it is too risky, and not worth the effort, sorry.
Best of luck to you if you try though