Just a little insight from an IT guy. Its likely your buyers work for or sell to sanctioned governments. Russia, china, Iran, and North Korea cannot get components needed to make high tech weapons. Most of those chips are made or were made in the US. Since they are sanctioned (in this case especially russia) is scrambling to replace battle field losses they are paying exceedingly high prices in the scrap market because they are able to repurpose these chips on boards used in array of weapons.
I can understand from your perspective that buyers offering extra value are all the same, but selling to those entities could backfire, if intelligence operatives working for the allies figures out that the buyers you are selling to are connected to any one of those countries, an I didnt know response from you wont be enough, theyll bankrupt you at the least, and at the most charge you with espionage or supporting sanctioned regimes. Now that a new set of sanctions have been ratcheted up, it's the sellers responsibility to vet their customers to make sure it isnt an individual or country controlled company working for said sanctioned regimes.
The chips you are looking for fall under the recent sanctions forbidding the transfer of said chips to those countries, china mainly needs chips used to run A.I so its least likely of the four.
Your buyer is likely working for the russians or Iranians to keep their production of missiles and drones up.
Just my 5 cents, obviously I can't stop you or prove my claims for certain, but anyone buying up obsolete chips for way more then scrap value, is likely connected to one of those unfriendly countries who cannot openly do business with USA, UK, and other NATO countries.
