1) The Mishna (49a) & Gemoro discuss overcharging by a sixth. It seems this is speaking about someone who charges more than the market price for an item.

Is this connected to the expected profit that a merchant can make on selling an item (mentioned earlier daf 40b)?

i.e. merchant buys item (of essential living) for 6 shekel, he is allowed to sell it for 7 shekel - if everyone does this, the market value will be 7 shekel. I assume the sixth of our Mishna is then a sixth on top of the 7 shekel - is this correct? (it just happens that both increases are at a sixth).

2) According to Shmuel (49b), the sixth of overcharging can be either of the value or of the price paid. e.g. item worth 6 shekel, if sold for either 7 or 7.2 shekel - that is a sixth.

What if the item was sold for 7.1? Does Shmuel say it is bitul mekach (since more than sixth of value) or mechila (since less than sixth of price) or also Onaah (since in between 7 and 7.2)?!

Meir Eliezer Bergman