Note that the second list is just tiers, you can trade in without actually losing any. We just did a Difficult II, and with 200 hallmarks, I got the NQ feet. Went back to the other menu and still have my 200. Sweet~
That being said, each tier can obviously only be gotten once. Got 12 Remedies as my first reward, went back for a second helping and got nope'd.
Also, limited number of items for augmenting. He said he could only offer me 20 more things of sap. I bought one, and he could only offer me 19 more.