Since soda pop is carbonated to a much higher level than beer, there is absolutely no reason why you couldn't use a soda bottle to package beer. Most homebrew supply houses now carry brown PET bottles and caps. Also, most homebrew shops carry a special cap for you to artificially carbonate flat beer in a 2-liter soda bottle.
In fact, I always bottle one plastic soda bottle at bottling time. I fill it as normal. Then, after I remove the bottling wand, I squeeze the bottle until the beer is forced all the way to the rim. That's when I cap it. The sides of the bottle will retain the squeezed-in shape. As the beer carbonates, the squeezed-in shape will be forced out. Thus, you can judge the carbonation level in the beer by squeezing the bottle.
You should note that an unopened plastic soda bottle will be rock-hard, compared to a perfectly-carbonated plastic bottle of beer, due to the higher levels of carbonation in pop.
I wonder, though, why you're not buying glass bottles. I mean, PET bottles - especially the caps - wear out rapidly. Heavy brown glass beer bottles with pry-off caps last pretty much indefinitely. Here's a tip that will not only give you a supply of bottles; it'll also make you a better brewer: If you're considering making a certain style of beer,
look up the benchmark commercial versions and buy a case or two of that. At the end of your supply, you'll have two cases worth of bottles and a very definite idea of what your proposed beer should taste like.
You dig?
Bob
