I trust you mean this one :
That sphere box set is hard to find...you can get your hands on it if someone you know is in the UK. Amazon, anchorbay et al carry it on their UK sites.
Be informed that its Region 2 encoded. You need a Region 2 supported player to run those discs.
If you need it, its on eBay too right here :
http://cgi.ebay.com/PHANTASM-1-2-3-4...QQcmdZViewItem