Buy UA miles for 1.66c (Purchase IHG pts w/bonus by 15 June '18 & xfer to UA w/bonus)
Until 15 June, there's a 100% bonus when buying IHG points. That makes them 0.5c/pt so long as you buy 26k+. (i.e. 52k+ after bonus)
Until 30 June, there's a 50% bonus when transferring IHG points to United miles. You earn 3k UA miles per 10k IHG, instead of the usual 2k. That makes them 1.67c/mile.
Given that 1.86c/mile is about the least UA has charged in recent times during promotions and 2c/mile appears to be the cheapest price when buying additional miles on an existing booking, this seems like a good deal to anyone who was intending to buy UA miles.
There's a maximum of 200k (100k bought + 100k bonus) on the first offer, so that means a maximum of 60k UA miles can be bought this way.