$10k is the number I keep hearing where transaction reporting is required. I know that when I paid for my last car the Credit Union officer wanted to know what the debit was for.

BTW, One of the local car dealers spent time in lockup for his part in selling a car for cash and hiding the sale in a series of under the limit cash payments. If I remember correctly the buyer was a suspected drug dealer.

I can't see the IRS getting excited about you spending tax paid money. Inheritences happen all the time. But dropping big bunches of money without much to show for it... It's hard to say if any attention is going to be noticable.