I mentioned about buying points in the Beginners' Guide I updated not long ago. A minimum balance of 10000 is required to kickstart the “5000 points for $35 trick”.
My usual advice with buying points is that you should always have a specific use in mind before you buy them. This is because it is rarely good value to speculatively buy them for future use. Instead if you spot a hotel with a cash price higher than the cost of points, then you should pay with points instead. This is perhaps the cleanest and simplest forms of arbitrage, easy win if you are new to the points ‘game'.
The 75% bonus only kicks in when you buy 20000 points which then gives a 15000 points bonus. While the price per 1000 points increment starts off at $13.50, there is a price quirk at exactly 26000 points where this drops down to $10 per 1000. So it is in fact cheaper to buy 26000 points and receive a total of 45500 points than to buy 23000 points, 40250 total!
Bear in mind that occasionally IHG sells points with a 100% bonus so this is not the most generous deal outright but if you need to buy an expensive half-term or Easter trip and need the points to secure your room instantly then this is the way to go. Use this link to access the ‘buy points' page.