Prices at the local markets vary from day to day, sometimes drastically. Supply and demand at its best. This is especially the case for non-farmed products like crab, squid, sea fish.
And, of course, here you ALWAYS haggle, whether you buy two bananas or 10kg of shrimps. Sometimes this gets tiresome.
Today we bought 3kg of clams for me (1-1/2kg for lunch, the other half for dinner). 55,000 Dong – about 2.25€ – 0.75€ per kg. That would be a good price