The propane regulators seem to wear out, become clogged, or otherwise fail from time to time. (You don't cover or protect the regulator from the elements as recommended, do you?)
Instead of looking for a used device, you could explore replacing the assembly with new parts. This is all part of the fun, looking for new parts to repair old systems.
It seems that the Commercial Pro unit uses a 10 psi output regulator like in this picture from mosquitomagnetrepair.com. The Defender and other traps come with a standard propane grill regulator with about 11 inWC (inches of water column, about 0.4 psi) fixed regulator, but this is evidently not that. ... The so-called "high pressure" regulators are generally adjustable in the range of 1 or 2 to 20 or higher psi. The one above looks dealer marked "10 psi" and seems to be fixed at 10 psi. One web page shows the KLI International model 9000 regulator shown as 0-30 psi adjustable (presumably by a screwdriver adjustment under the cap).
Your existing hose assembly with the quick connect adapter might be connected to a new regulator using an appropriate fitting. For example, this $18
regulator comes with 4 fittings. Perhaps one of these fittings will match your existing hose. (Odd that they seem to include the yellow gas fitting tape, but don't use the tape on the threads in their illustrations.) I don't know anything about gas hose barb fittings, but I doubt it is rocket science, or at least we don't want it to be, so ask a plumber.
Alternatively, you could consider getting a new hose with the "quick connect" connector, if that is available. I had to use some fittings to replace the regulator in my Defender. See this
blog post and adjacent posts.