The C13 (often referred to in industry as an IEC cable) is an absolute standard for computer PSU mains connections. Cables with 15A north american mains (NEMA 5/type B) male end* and IEC female end are thus ubiquitous. Note that the HP PDU, since it's intended for direct use with computer equipment, features female IEC connectors. So you need an IEC->IEC cable (commonly referred to as IEC Extension) rather than a mains->IEC cable to connect devices to this PDU. These cables are a little less common, but still cheap.
Note that the dryer receptacle you have now (probably a NEMA 14) will not be matched by the connector that comes with the PDU, since data centers almost universally use the NEMA L-series "twist-lok" connectors for mains service. So, you'll need to splice on a new cable, which you should be careful with since this will carry around 240v 20A (plus or minus a lot, depending on machine load) in the configuration you describe. In an enterprise environment any non-locking connector is considered a hazard (unreliable, unsafe), and I think this should be wisely carried to homes. What I'm saying is that it might be worth it to have a twist-lok connector installed.
(*) In the theatre industry we call these Edison plugs. I'm not sure how common the term is in IT. There are a lot of standards that define these plugs, NEMA 5 is cited the most.