All of the above blades and cartridges were purchased during May/June/July 2020 from Amazon, CVS, eBay, Wizashave, Hy-Vee, Italian Barber, Walgreens, Harry's, Dollar Shave Club and Defender Razors with the exception of the original Gillette Sensor NOS cartridges. I had several unopened boxes of those from the late 1990s. Since they're no longer being manufactured the NOS cartridges and blades were quite expensive to source so their costs aren't really a good reflection. I probably shouldn't have included them but this wouldn't be as fun without the walk through history.