party centre is also between 4dhs and 5dhs...
do u need a lot of balloons done? if so the best thing to do would be to buy a helium cylinder and fill them urself... the cylinder costs AED 150 and can do MANY balloons...
else... if u only have a few to do why not think of regular air balloons but to give them the helium effect stick them high up on walls/other elevated surfaces...
just some thoughts :)