If you want a PLB (a real PLB, not a SPOT or InReach version), it might be best to wait a bit. A new feature is just being introduced that is terrific. It is called Return Link Service (RLS) and is a notification from the satellite back to the PLB that your distress call was received and is being processed. Otherwise, you don't know until the helicopter shows up. So far, for consumer units, I think only two units have RLS: (1) the sMRT Shield (from the UK), which I don't think is actually in production yet, and (2) the McMurdo FastFind ReturnLink unit from Orolia Maritime (now SeaSolutions). See
https://www.seasofsolutions.com/wp-content/uploads/FastFind-ReturnLink™-Personal-Locator-Beacon-A4-v3-10-23-19.pdf.
Again, I don't think the new FastFind is for sale yet, but the RLS is worth waiting for.