You can still find the PS+ "essentials" subs for under $40 now and then. But if you want "Extra" or higher, you're gonna pay.
For me, I had over 400 days of PS+ "essentials" (due to code stacking), and I upgraded to "Extra" for the entire duration and it was like $40... for over a year.
I always turn off auto-renew bc they charge you full retail price which is quite a bit more $. Same with every subscription service (AV, Sam's/Costco, TV services, etc)
And yeah... PS+ games "expire" if your sub expires. But if you renew they become available again.
Check out slickdeals.net and set up an alert for PS+ for the code deals. You can't always find them on demand to so better to get alerted and stack up.