So the prices are 400, 800 and 1200 points, which translates to 1.2 points per penny, £3.33, £6.66 and £10.
Are there smaller points amounts purchaseable than 2100? That's a snidy little sales number there! Paying in units of 400, after a few purchases you'll have 100 - 300 points left over, and if you want another 400 point download, that'll be another £17.50 you'll have to spend to get it. That's why a nice round 2400 point card isn't sold!