Is there any basis in the Sunnah for organizing opening ceremonies for Musjids?

Answer

At the best, these Musjid opening ceremonies (iftitaah functions) are futile, and at the worst, they are bid'ah. There is no goodness in these functions of riya (show) and israaf (waste). There is no basis in the Sunnah for these wasteful and ostentatious functions. It will not occur to the organizers and the Ulama who condone these practices to contribute the money to the poor. The world is flooded with poor and destitute Muslims. But, our people squander huge amounts of money on riya, takabbur and israaf.

The only specific way of beginning a new Musjid is for the Muath-thin to announce the Athaan at the very first Salaat. There is absolutely no ceremony and no other way for the iftitaah of a Musjid. These ceremonies and functions are the ways of the Ajam.