There's a lot of debate on these boards about which system has the better value. I don't feel the data is correct though because I have never paid full price for LIVE. It seems as though there is almost always a sale going on by some company, somewhere. I'm sure the same could be said of PSN as well.
Anyway, my current year subscription of LIVE only cost me $40. That's only $3.33 a month USD. I'm fairly certain I've seen it cheaper. For those PSN guys that seem to like this board for some reason, I'd be interested to see what kind of sales you have experienced too, both price and frequency, as it's not something I often search for. --- "The best way to get the right answer on the Internet is not to ask a question, it's to post the wrong answer." - Cunningham's Law
You also need to consider that probably a lot of PS+ users got their first subscription at that time, since PS+ was not obligatory for playing online on the PS3, but became so for the PS4.
Therefore, it's very likely that not many people have information on the frequency of the PS+ deals before that. More importantly, now that the PS4 does need a PS+ subscription for multiplayer, it's very likely that the frequency of deals will change (for better or worse).
We will get a better idea when this year's Cyber Monday deals come out and we can compare them to last year's.