The number of bonus miles accrued varies on a sliding scale, starting at 20% for small purchases and maxing out at 40% for purchases of 30-40,000 points. Here’s the breakdown:
Points are normally priced at $27.50 + 7.5% tax for every 1000 points, a smidgen over 2.9 cents each. With this promotion the rate can drop just under 2 cents per point which isn’t horrible but also not incredible either. Certainly easier than trying to find a 2cpm mileage run on Alaska though.