Forget the glues and forget oxy/acetylene unless you are an EXPERT body man. You get what you pay for, plain and simple.
If you want to do this particular project right and and to do body mods for many years to come, invest in a quality MIG system. Your $400 will definitely not be wasted but will buy you most of a quality system like a Lincoln model 120 that will last a lifetime of hard use.
If this is a one-time project, farm it out to a pro shop, you will be bucks and headaches ahead.