It is not permissible
to give money for such a Kaffarah. Rather, you have to make the Kaffarah for breaking your oath as mentioned in the following Ayah (Qur'anic verse):
Allâh will not punish you for what is unintentional in your oaths, but He will punish you for your deliberate oaths; for its expiation feed ten Masâkîn (poor persons), on a scale of the average of that with which you feed your own families, or clothe them or manumit a slave. But whosoever cannot afford (that), then he should fast for three days. That is the expiation for the oaths when you have sworn. And protect your oaths (i.e. do not swear much). Thus Allâh make clear to you His Ayât (proofs, evidence, verses, lessons, signs, revelations, etc.) that you may be grateful.
Moreover, you have inverted the Fatwa (legal opinion issued by a qualified Muslim scholar) that you ascribed to us in the question. The correct Fatwa is that the Kaffarah is to feed ten poor people by giving each of them half a Sa` (1 Sa`=3 kg. Approx.), to clothe them, or to free a believing slave. (Part No. 23; Page No. 10) Only in case of the inability to do any of that, you can observe Sawm for three - preferably successive - days.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.