Ballons are made to float in air with helium. Helium is suitable for filling both, latex- and foil-balloons.
Helium capsule is suitable for example for one day events to fill a needed amount of balloons and then easily recycle the capsule.
You can find it here: https://pood.ohupallikeskus.ee/tootekategooria/heelium/
It is relatively easy to obtain helium. You can rent helium containers and filling-apparatus form AGA service-shops.
AGA service-shop network covers whole Estonia. http://www.aga.ee
Numbers of balloons that can be filled:
Hi-Float is a special gel that is inserted into the latex-balloon to make helium stay in the balloon for longer. As usually helium escapes form the 12“ balloon in 10-12 hours, then adding the Hi-Float gel extends the period of the helium escaping to 3-4 days.