Interestingly, the book The eclipse of the 'Abbasid caliphate; original chronicles of the fourth Islamic century, contains a slightly different account, suggesting that a huge ransom of fifty thousand dinars was offered, but never actually paid:
In this year the Qarmatians restored the Black Stone to its place in the Sacred House of Meccah. It had been taken thence by Abu Tahir Sulaiman b. Hasan Jannabi. Bachkam had offered for its restoration fifty thousand dinars, but his offer had been declined, with the message: We took it by order, and when an order comes to restore it, we shall do so. When Dhu'l-Qa'dah of this year came (began April 11, 951) the brothers of Abu Tahir wrote a letter wherein they stated that they were restoring the Stone by the order of him by whose command they had removed it, that the ceremonies of the pilgrims might be performed completely. The person who brought it was Abu Mohammed Ibn Sanbar, who presently took it to Meccah, and restored it to its place.
The account was written in the book The Experiences of the Nations by Ibn Miskawayh in the tenth century, so is an almost contemporary source writing closer in time to the events he was describing than Al-Juwayni, who was the source cited in the Wikipedia article in the question..