There is no problem in selling balloons and other such playthings of children. However, if these games harm others or the children are spoilt due to them, then avoiding such games is compulsory.
As given in Radd Ul Muhtaar, Kitaab Us Salaat.
And Allah Most High knows best.
Mufti Syed Ziauddin Naqshbandi Qadri
[Professor, Islamic Law, Jamia Nizamia,
Founder-Director Abul Hasanaat Islamic Research Center]