Everyone's not seeing the real damaging issue here:
30k is 30k, heck he could of attained that money in numerous ways in which it would not have violated any NCAA rules. The 30k is not the fact that damns Duke.
The most damaging issue is whether a regular Joe Shmoe college student (non-athlete) could have attained a $100,000 luxury jewelry purchase by only paying 30k upfront and the jeweler feeling comfortable enough to lend him the remaining $68,000 to be paid in 15 days. The answer is No. If anyone thinks that his status as a Duke basketball player and future earnings of the NBA did not play a role in the jeweler feeling comfortable enough to have him walk out of the store with only paying a 1/3 of a $100,000 bill your sadly mistaken. There's a rule the NCAA enacted called "Strict Liability" which is for purposes like this. If any college athlete is afforded special privileges that are not afforded to a regular non athletic college student, that player is deemed ineligible and any games in which that player participated in are erased.
Duke has done nothing wrong at all, but are going to get bit by the stupidity of one of their own. Maybe I'm wrong but the case is pretty cut and dry as I see it.