Bongs are a real investment to make.......... Most "glass blowers" are really "lampworkers". Lampworkers use a torch stationary on a bench. Then there are other types of glass blowers, lathe operators. Those are the bong people. In addition to all the glass, kiln, torch, tools and fun equipment, they also need the lathe to hold tubes while they make the finished product. A good lathe is anywhere from $6k-$15k depending on what you want.
The cost to get started is the only real reason bongs arent selling for dirt cheap. Soon as more people start to make them they will drop in price quite a bit.
For now if you just want a cheap big bong look for an acrylic one. They are crap, but you get some gigantic sizes for inexpensive cash.