I think limes must vary in price more than any other fruit. A few months ago you could get them everywhere for one baht each. Then the price began to climb until a bag of four costs 25-30 baht at the supermarkets in town.
A week ago I bought them for four baht each at the fresh market near our house. A day or two later a lady with a cart came down our street selling limes and bananas. I bought a bag of four limes for five baht.
Today on the way home from lunch we passed a truck selling very nice limes for 20 baht per kilo (about 40 limes).
So, in the space of two weeks we have limes priced from a high of 7.50 baht each to a low of .50 baht. The most expensive cost 15 times what the cheapest are selling for. Amazing.
(Why do I care so much about the price of limes? Easy. I drink a lot of gin and tonics.)