Supercheap sell them for $30-40 odd dollars...

I've tried all different methods without spring compressors, all of which are not safe. Spend a few dollars for you own safety, please!

Having said that though, the best method I used without them was to lay the strut flat on the ground, hold the strut/spring with one foot (make sure you have it facing away from you or any valuable objects). Then hit the centre nut with a rattle gun. Once the nut is out the strut would shoot across the floor. Rather than the top hat flying into your face.

To get it back on I either got a mate to hold the top hat. A few times I did it with my own weight, not easy though.