Just in case someone is interested in my inflation technique, here it is.
I have a small air compressor in my shop, so I installed a regulator and ran a hose under the house into my bedroom closet. I normally run 5-10 pounds, which keeps the balloons from inflating too fast to control. The other day I came on another idea. I use a Milton blowgun, which has standard ¼" pipe for the nozzle. I bought a ¼" pipe cap, drilled a tiny hole in it and put in over the blowgun's tube. Now the balloons inflate r-e-a-l-l-y slowly so I get the thrill of watching them get bigger...and bigger... and bigger until they're the size I want, or (sometimes) until they go BANG!
You might try adapting the idea of really SLOW inflation to whatever you use.