Through Friday, June 15, IHG Rewards Club is offering a 100% bonus on purchased points, meaning you can buy up to 200,000 points for $1,000, or 0.5 cents each, when you buy 52,000 or more points (lower amounts cost more per point).
This is pretty cheap for IHG Rewards Club points
You can always buy unlimited IHG points for between 0.6 and 0.7 cents each year-round with the "points and cash trick:" reserve a room using points and cash, refund the reservation and your cash co-pay will be refunded in points. So a 50,000-point night that you book with 30,000 points and $130 in cash, then refund, will allow you to buy 20,000 points for $130, or 0.65 cents each.
Still, 0.5 cents is 20% less than 0.6 cents, so if you have upcoming travel plans that are good IHG redemptions at 0.6 cents, they'll be even better redemptions at 0.5 cents each.
You can also earn portal cashback at Points.com, which handles these transactions for IHG, reducing your net cost further below 0.5 cents per point.
IHG Rewards points aren't very valuable, but they're more valuable than that
IHG Rewards points are often worth between 0.5 cents and 1 cent each, so purchasing points at 0.5 cents each speculatively could reasonably be expected to translate into a discount of perhaps 50%, after taxes, on a future stay. That's not bad, especially if you aren't able to manufacture Hilton or Hyatt points in sufficient quantities to meet your travel needs.
Of course, there is a maximum points cost of a free night award of 70,000 IHG Rewards points (for now), while there's no limit to the cost of a paid night, so there's no theoretical limit to the value you can get.
IHG award availability stinks
The problem is that at the properties where you could expect to get the maximum value for your IHG points, award availability is extremely limited. Not only are properties like the InterContinental Hotels Bora Bora Resort Thalasso Spa extremely stingy with award space, what space does become available is quickly snatched up due to IHG's willingness to sell points for so much less than their redemption value at those properties.
A huge pool of cheap IHG points chasing scarce award availability makes people even more desperate to book rooms when they do become available, even holding onto reservations and rooms they don't plan to actually use.
I like the example of the InterContinental in Bora Bora because it has an entire FlyerTalk thread dedicated to folks trying to find award availability there, but the same is true of many desirable IHG properties during periods of even medium demand.
If you have firm plans, have identified an IHG property that provides good absolute value (I'd aim for 1+ cent per point) and relative value compared to any other hotel currencies you have available, and have confirmed the property has reward nights available for the dates you're interested in, then this is an opportunity to buy points at a decent discount compared to the price they're sold for year-round.
But if any of those conditions isn't met, then under no circumstances would I buy IHG Rewards points speculatively.