If what you want is Verbatim Double Layer DVD+R media with a "MKM 003" MID, then you should just buy 8x certified Verbatim DVD+R DL media.
There is (currently) no need for the shop to list the MID for these Verbatim DVD+R DL 8x media - you will always get MKM 003.
The "MKM 001" is used for Verbatim 2.4x certified DVD+R DL media.
This media will burn up to 8x in some drives however, and I guess it's possible that some shops will use that fact in their marketing.
With many other DVD media it's necessary to see the MID in order to know what you're really buying, but in this case it should be straight forward!
When in doubt you can also use the Verbatim "product number" (in EU this is called a "reorder" number) to check which media someone is selling. The product number for Verbatim DVD+R DL 8x media in 5pc jewel case is 95311.
Look here at Verbatim's page for that product.