I lucked into the pair with manifold and a third, solo. I had been looking for 2 tanks to solo each and came across a listing on craigslist. My thinking was, "Three 2011 steel 100cuf tanks for $300? That's a great deal." Then I started seeing prices for twinned hp100s (600? 650?) and started thinking about selling the pair, then buying one more tank someplace else. Any thoughts either way?