Vinylmaster pro is cheap and works with cx300 on windows 10, this machine was released in 2001 so if the seller says it's a few years old he's lying. The machine may still work perfectly though, just make sure you do a few test cuts with different sized circles (around 1 inch), see if the edge is nice and smooth and if the lines close properly. Test it on high speed (60-70cm/sec). Test the 'eye' too, if it doesn't work the machine has lower value.