If I can offer a little perspective re the cost of a lot of products.
I am in Australia and we are having the same problems. The major supermarket I shop at is suspending weekly specials as they can't guarantee supply due to changed logistics (they said they take six months to plan Christmas but did three Christmases in one week from a standing start when all this panic buying started).
On supply,
A) Australia has been in horrendous drought for a few years. This means vastly reduced harvest in cereals, meats, fruit and vegetables. For example, one of Australia's largest rice growers was on tv on Sunday saying he has only planted 40 hectares because that's all the water he could get. If that is repeated across a whole industry, it's going to be noticed. Think beef farmers who normally carry 10 000 head hanging onto about 100 of their best cows and a couple of bulls for the last couple of years. Also repeated in the sheep industry. After rain last month, all those farmers are going to want to restock so that means fewer killers going to the abbatoirs.
B) Australia has had huge bushfires, as had California. Both enormous producers of fresh fruit and vegetables. Stuff may be burnt out, not picked because they were banned from moving people and trucks and had to be left in the paddock, smoke tainted or, here anyway, then flooded.
C) With Australia in drought, much of East Africa was up to their necks in flooding. Any fruit and vegetables there will be lost for months.
D) African Swine Flu is killing pigs left, right and centre. Again, on such a scale that the world order in the industry is hugely disrupted.
There has been a growing level of publicity that the harvest of the UK's own supplies is going to very difficult between Brexit and isolation.
The logistics of food is a worldwide circuit and there have been immense natural disruptions. That it's happening now (including in my local Perth greengrocer) with all the economic distress is just the worst timing.
Please remain kind to your supermarket staff.