I don't understand

Here are the prices for each of the seasons of Roseanne on Amazon:

Season 1: $5.02

Season 2: $5.49

Season 3: $33.61

Season 4: $87.21

Season 5: $134.99

Season 6: $30.46

Season 7: $23.74

Season 8: $33.97

Season 9: $23.70

WTF?

I'm going to have to take a break from this and consider my options...