I've got a PST 100. I believe there was a bankruptcy involved and several years of non-production. This is from their news page mentioning their re-organization and return to scuba:
"
PST Scuba to Exhibit at DEMA Show
October 17, 2006
E-Series Steel Scuba Diving Cylinders Return to Dive Market
PST Scuba extends an open invitation to attendees and fellow exhibitors at DEMA Show 2006 to visit us at Booth #2182.
E-Series steel diving cylinders, featuring PST Scubas original hot dipped galvanized finish, will be on display, and our staff is ready to share both product and company news.
PSTs reorganization earlier this year led to renewed focus on our core product lines of scuba diving tanks and aircraft cylinders. PSTs long-planned relocation to Cudahy, Wisconsin was completed in September. New production facilities and equipment, improved inventory control, and a firm commitment to customer service are the driving forces behind a new and improved PST Scuba.
Recognized for innovative cylinder design, quality and safety, PST Scuba is excited to bring our original E-Series steel scuba tank line back to the DEMA Show. We look forward to seeing many of you in Orlando."
I checked out several of their dealers and the only one I could find advertising PST tanks on-line is Larry at Scuba Toys.
AL