Take a look at this site:
https://www.facebook.com/The-Ghosts-of-the-Eastern-Front-451074868343353/?fref=ts
For all you non-facebookers:
http://stalingradfront.com/
These people allegedly are called “white diggers” who are supposed to cooperate with official authorities to re-bury the KIA’s they discover. Would you consider this as valuable work or just as modern-time grave robbery?
Maybe I missed something, but I didn’t see anything on the linked site to establish that the listed items were found in graves.
Scrolling through the site, I doubt that many of the items are genuine. I suspect that it’s been salted with a lot of helmets which probably aren’t genuine and which have been improved with nice new badges etc, although the badge improvements etc are acknowledged.
Probably just capitalism / commerce at its amoral best, as practised in Russia’s current laissez faire economy in the same weird fashion that China pays spiritual homage to its communist heritage while being a rampant capitalist economy run by the Party communists who profit magnificently from their control of that bizarre economy.
But your post does raise the difficult question: Who owns, or perhaps who should control, personal (i.e. items of personal equipment as distinct from, say, sunk war ships) war relics?
Standard issue uniforms, webbing, helmets, weapons etc were not, as far as I’m aware, the personal property of service people in any nation in WWII, and probably not before or after in 20th century wars. Although some of us may, by administrative or other accident, still be storing issued items in the expectation that the authorities will in due course collect the items they failed to collect upon our discharge, with thanks to us for preserving these items at no cost to our government. 
And, in my case, an item I bought privately with my own money because it wasn’t issued and which now, although not then, is a controlled weapon and hangs in my garden shed in its khaki scabbard waiting for some cop with nothing better to do than charge me with having - WAIT FOR IT - a machete.
If one of the helmets with a bullet hole for sale on the linked site belonged to, say, a father who died from the bullet which made the hole, I’d expect that the descendants would see that as considerably personalising the government issued helmet.
If one really wants to pursue this line of thought, where does it take us with items such as Japanese soldiers’ and even civilian corpses’ skulls treated as trophies by Western forces which would have been outraged if their troops had been subjected to the same treatment?
http://time.com/3880997/young-woman-with-jap-skull-portrait-of-a-grisly-wwii-memento/
http://bangordailynews.com/2010/08/26/news/bangor/japanese-trophy-skull-finally-returning-home/
Relic Hunting was a popular pastime in the Area of Tennessee where I lived, but if a grave site was discovered, everything stopped, until the authorities could exhume the remains for proper burial. There were two Cemeteries in the area that would take them, one for Union, and one for Confederate. As long as the relics recovered were not taken directly from the dead, it is considered appropriate. But to pick over the remains of a man for trinkets is unacceptable.
Local authorities should be removing the remains, and as they are found. Those men may still have family somewhere who would like to know about their people being found.
I watched a video of an excavation of WW I trench lines, they did recover remains, and had the proper folks there to recover, and send them along to the proper Governments. Battle of the Somme https://youtu.be/0LO1dYuI6g0
I agree that some of the stuff shown on you tube etc. is grave robbing. pick the fields, and the hills, but leave the bodies alone, move along, and report them. One thing to take a trophy from a man you’ve just defeated, wholly another to rob a long dead corpse.
That sums it up.
The first, unpleasant as it may be to many, is understandable in the heat of the moment. The second, done decades later purely to profit from the dead by those who risked nothing in the conflict, is just despicable.
And then we have this remarkable Japanese veteran who did everything decades later to honour his wartime comrades, at his own cost.
Why France and England didn´t declare war on the Soviet Union as they did on Germany based on the defense of the polish state independence?