First: A lot of people are fragmentizing their low priced items because of the Achievements. Second: A lot of people are hoarding the same items for the Achievements. Third: People got sick of restocking because of the low prices and now they incrase of course. Fourth: Like mentioned before, plushies and beanbags are turned in for Achievements.
There are propably more reasons but, why don't you just use this inflation? Go restocking and making some money, there is not better time for it then now!
Wow I had no idea they stopped vending food. Shows how observant I am.
Thanks everyone for posting theories!
Side note to the black candy bars... why did they choose that for an achievement??
Drawmeastar: Correction, you did have lots of under 1000 sP items in your shop.
Really? Then this would be a good time to price the stuff in my shop hahaha