hey guys i figured i would share how i found a ps4 pro on 3.70 in feb 9 2018 (coincidentally my bday)
i will preface this by saying that i am a sample size of one and it may vary
you need to be able to look at the box in person, i went to a small town near me and to a store that is not known for selling consoles. for me this was a shoppers drug mart
i asked them to grab the oldest looking ps4 pro they had and to look for the dustyest one that had been sitting there for the longest. at this shoppers it was the manager grabbing the console so she should know roughly which ones had been sitting for a long time.
what you want to look for is the games on the back of the box, you want to find one that has games listed as "coming 2017" mine has horizon zero dawn and mass effect Andromeda listed as that
what i did from there was buy the console, go out to the parking lot and open the box (carefully i wanted to be able to return) and it said on the back of the ps4 pro manufactured 2016.
thats how i got a ps4 pro on 3.70, hope this helps someone find one!