Telling friends that a particular vendor is extremely expensive is not an issue of LoshonHoro. In fact, if they are more expensive than the proper amount, it is an issue of Oina'ah, deception, as the vendor is deceiving their customers by charging them more than reasonably expected. Even if they are overcharging them by less than a Shtus, one-sixth of the deemed proper amount, since it is still considered a loss for the clients, there is no Issur of Loshon Horo, according to many Poiskim. On the contrary, there is an Issur of Lo Saamoid al Dam Re’echo, the Biblical prohibition of not standing idly by as one’s fellow’s blood is being shed, which in this case would mean the obligation to protect people so that they should not have to spend more money than reasonably expected. While the ChofetzChaim is strict in this regard if the extra amount is less than a Shtus, most Poiskim do not consider this LoshonHoro, as it is actually protecting the consumers.