Every live buy-points and buy-miles sale across airline and hotel programs, with the bonus percentage, the effective cost per point and the date each promotion ends.
The math here is not complicated. Work out what the points will cost you per point, then work out what the award you want would cost in cash. If the cash fare is meaningfully higher than the cost of buying in, the purchase makes sense. If you are buying because the sale looks good and you will figure out the trip later, you are speculating with money that does not earn interest and cannot be refunded.
The strongest use of a points sale is closing a small gap. You have found the award, you are a few thousand miles short, and buying the difference costs far less than the cash ticket. This is also the case where the sale itself matters least, because even at standard pricing the purchase often still beats paying cash outright.
Purchased points are almost always non-refundable, and they sit in one program with no way out. Find the seat first, then buy. Award Travel Finder searches live award availability across programs, so you can check the seat is really there before a sale talks you into a balance you cannot use.
If you already hold Amex Membership Rewards, Chase Ultimate Rewards, Citi ThankYou, Capital One miles or Bilt points, moving them across is often cheaper than buying in with cash, and a promotion can tilt it further. Check our transfer bonus tracker alongside this page before you reach for a card. The two promotions rarely line up, but when they do the combination is about as cheap as a redemption ever gets.
Most programs run points sales several times a year, so missing one is rarely fatal. The exception is a trip with fixed dates where award space is already thin, and waiting for a better promotion risks losing the seat entirely. Money saved on a ticket you could not book is not a saving.