Guru.. will try once.. and tried with hydrogen, but not enough force to blow up the envelop.. so atill waiting to realize the craft..

hey i know its little late to reply to this
i found balloon time on amazon here's the link http://www.amazon.in/American-Balloon-Company-324756-Helium/dp/B004XHWCSY/ref=sr_1_1?ie=UTF8&qid=1453195301&sr=8-1&keywords=helium+tank
here's another one for cheaper
http://www.amazon.in/Balloon-Time-296933-Helium-Tank/dp/B000TVFDO8


I even wanted a helium tank for my project but couldn't find any in indian online shopping website.I had an idea i searched helium tank  on amazon.in website about 20-30 times in total.About a month later now they are selling helium tank.You can try same when you don't find anything you need or you can just call them and tell them what you want but calling them didn't help me.hope this helped

and another link
http://www.marsgas.net/helium-gas-cylinder.html#balloon-gas-helium-cylinder

Why dont we produce H2 instead. lighter than helium, ive seen a simple apparatus using acrylic for producing h2 with few electrodes and a car battery.

because h2 is highly inflammable

Yeah, but for smaller experimental purpose, im sure no big harm with H2. ofcourse ive seen those video of h2 balloon bursting. but they are because they are filled with both H2 and O2.

Hi, Here is the solution for your question you can buy helium gas at sp4mm3r they are providing helium gas cylinders in different sizes at an affordable price for customers convenience. thank you
http://www.sp4mm3r.com/