Question about season tickets

I was looking to get season tickets in the 500-600 sections. I know about PSLs but still confused on how they work. If I buy a PSL does that obligate me to get season tickets every year or just gives me the option? Also on the PSL website, I see the price of the season tickets for all the other sections besides 500-600. Can anyone give me a ball park range of how much season tickets will cost in these sections? Any advice/help is appreciated.