A few quotes from the Rabbi on 'Traditions of the Fathers'
in which he instructs the halakha to refrain from "purchasing mitzvot" if their price is deceitfully raised
Concerning the case in which an individual gave a sum for a mitzvah, and some people were aware that he was required to do so, for yahrzeit or an expecting woman and the like. Should those people raise their bid with no intention of purchasing it themselves, in order that the individual in question add to the sum, and agree in advance with the treasurer that should the individual stop bidding they are to pay only part of the sum – This matter is one of deviousness, trickery and deception…" I will deal with all his oppressors". For the one who seeks to purchase is being oppressed to the point that they are obliged to add [to the sum] out of self-respect…anyone with a soul will refrain from this and be rewarded.
HaShomer Emet, Laws Governing Purchase – Ki Tov Sachra, section 6, Halakha 6, A"M Hai, Lovorno, Palafji and Bilforti Press, 1849