"PX" means Post Exchange, or the "General Store" of an army post. "BX" is usually "Base Exchange" and is used by the Navy and Marine Corps. Within a Post Exchange is a military "boutique " that carries an extent of military uniform personal items from boot laces to sets of collar stars for a general officer. There are also available for purchases the various ribbons and medals that a serviceman is likely to accumulate during his time in service.
One can't buy a Medal of Honor, but just about every other medal is available to be purchased by anyone. It's not a violation of regulations to possess a medal not earned, but it is a violation to wear a medal not earned. Some individuals with lackluster military records would buy medals that they did not earn, or were entitled to wear, at the PX and wear them home on leave or separation. Hence, "PX heroes". The euphemism has since been applied to those who wear medals of suspicious circumstance. John Kerry's Purple Hearts, though authorized, are considered by many to be those of a "PX Hero".
Murtha has suspicious Purple Hearts and, as you state, many other medals have been handed out for next to nothing. The Vietnam War has a particularly unseemly history of an officer corps of bemedaled mediocrities and an army of under-decorated veterans and posthumously undecorated genuine heroes.
Thanks for the explanation--in WW2 I never got to any PX and only received my Good Conduct Medal at discharge---never got the others until after I retired and made plans to go back to Normandy for the 50th Remembrance in '94--only have 3 with the action star plus the Good Conduct with my "name engraved"(whoopdedo)on it--put 5 yrs in(12/41-2/47) but they did not seem to give out as many medals back then (we got commendation letters in our files)---can anyone get Murthas records as to the issuance of the Purple Heart?--I believe he was given the Distinguished Service Cross on retiring from the Marine Reserve--wonder how he was in Congress for 32 yrs on the taxpayers dollar and did his Reserve duties as well??---where his base is (Johnstown,Pa) has a bunch of unionized guys and most are 'Rat' to the core (don't know any better)--you know how it goes--Dad was a 'rat'--Grandpa was a 'rat' and I will be a 'rat' till I die
Why are you suspicious of his Purple Hearts?