As ramrod wrote, they're $50 a set at Supercheap.
Put both compressors on opposite sides of the spring, then wind each one down equally - i.e. 5 turns on one side, 5 turns on the other side, rinse and repeat, until the spring is compressed. Then get out your rattlegun and remove the strut nut inside the top hat, carefully lift off the spring, and voila. (Had plenty of practice doing this in early 90s Group E.....)
You may also need a 'C' spanner to undo the gland nut on the strut tube. Kent-Moore used to make a special tool with a half-inch drive for removing gland nuts, but it doesn't work with Volvo gland nuts because the top of the standard Volvo gland nut has little raised sections on it, and the wizz-bang tool needs the top of the gland hut to be flat.
Some Bilstein gland nuts have flat edges (60mm or so nut) and can be undone with an hugemungus shifter. Other Bilsteins have gland nuts which need a C spanner, a Bilstein tool, or a Kent-Moore tool. The Bilstein gland nut tool doesn't fit on Volvo gland nuts, although it looks to be the correct shape.
Be wary of the stupid mental obstruction rumoured to be hidden inside 85+ strut tubes, which will prevent an aftermarket strut insert being placed into a strut tube, unless removed.