How are Beis-Din expected to prevent the shop-keepers from keeping false weights and measures?
Bava Basra 89a: By appointing inspectors to punish shopkeepers who keep them. 1
Bava Basra, Ibid.: But not for charging exorbitant prices. Rashbam: Because, if one shop-keeper charges too much, one has the option of purchasing from another store. See Torah Temimah, note 185.
Why does the Torah repeat "Lo Yih'yeh l'cha be'Veischa"?
Rashi: It is a warning that someone who retains two different measures will end up with nothing in his house - "Lo Yih'yeh l'cha" ? because of "Even va'Aven"
Bava Basra 89a: To teach Beis-Din to appoint inspectors to punish shopkeepers who keep false measures. 1
Sifri: It implies that it is forbdden to retain faulty weights and measures in one's house even if one does not use them to cheat. 2
Rashbam (in Bava Basra)): But not for charging exorbitant prices - since If one shop-keeper charges too much, one has the option of purchasing from other stored. However, one opinion in the Gemara maintains that one appoints even for peoplee who overcharge - due to swindlers.
See Torah Temimah, note 187.
What are the implications of "Gedolah u'Ketanah"?
Refer to 25:13:2:1:1. and note.