Rav Meir Mazuz had some interesting comments during a recent shiur about shmitta produce.

According to Radio Kol Hai, Rav Mazuz  railed against the sharp increase in prices for shmitta produce. He said:

there is the "hetter mechira" in shmitta. I am not in favor of using the hetter mechira, but people who have no other choice but to eat from this have great rabbonim to rely upon that allowed it, including Rav Yitzchal Elchonon, the Yisa Bracha, Simcha L'Ish, Rav Kook, and even Rav Ahron Kotler and Rav Moshe Feinstein.
There are those who sell the same vegetable sin shmitta that were in the stores before shmitta, but suddenly right after Rosh Hashana the price jumps fourfold. Why? Because it is shmitta! Idiots - why do you increase it fourfold? It is the same produce from the 6th year. What happened to you? It is shmitta, they have to sell everything for more... it is prohibited to do this. Why are avreichim treated as less than the farmers?
So, even though one shouldnt use hetter mechira produce, it depends on the merchants. If they charge normal produces, ok, don't rely on hetter mechira. But if, say, the store in Netivot sells cucumbers for 1 shekel and the shmitta store in Bnei Braq sells for 4 shekels! Why? Why are you stealing? Every shmitta year they set up a fund to support the farmers so they have with what to sustain themselves for the year? So why not also think of the avreichim? They don't have what to eat and live with the minimum - can you really sell to them at prices four times the regular amount?
We in yeshiva are stringent and buy from the shmitta store, but we look for the store selling at reasonable prices. Think of them [ the avreichim] no less than the farmers.one wise guy from jerusalem said to me "so what - because it is expensive we should eat treif? and I am printing my book soon so answer me quickly!" I said to him - if you are talking about treif, there is no argument, as you have to deal with the actual situation. But if you take the position that all the gedolim that allowed it and ate from it were eating treif , then that is it, this is where the "tchum shabbos" ends. print what you want and I won't answer you, and even if you print it a thousand times it does not matter as "wasted words don't last. You cannot say Rav Ovadia Hadaya ate treif, Rav Ovadia Yosef ate treif,.. what happened to you? there is a limit to the craziness!
So, it depends on the prices. They need to take into account the public. When Hillel the Elder saw people stop giving loans int he 6th year because soon the loans would be wiped out by shmitta, he established the pruzbol. The truth is it already existed,, but it was only in use privately as the Mishna says...but Hillel established pruzbol to make it widely used. Same thing with this.

words of gold.

The comparison between Netivot and Bnei Braq isn't that good because the store in Bnei Braq might be paying for greater overhead than the store in Netivot, so naturally his prices will be higher, but when the same store increase sits prices by 4 from before shmitta to during shmitta that really shows the problem.

I do not know why he is talking about this now, during the first year after shmitta is over and 6 years away from the next shmitta. Let's see him instruct people to eat hetter mechira, even if just to pressure the storekeepers to lower the prices, during the shmitta year and not 6 years before the shmitta year.