The Points Market now has a real interactive price history chart, just like the live sell listings. Tap or hover a point on the graph to see the exact price on that date, drag across the graph to zoom into a date range, and double-click (or double-tap) to reset the zoom.

Use the Last month / 3 months / 6 months / 1 year / 3 years / All time tabs above the graph to switch date ranges.