Regarding EZ Caps, I found buying 4 packs of Grolsch at my local beer store (Wegmans) worked out to $2 per bottle..which is about what they cost empty...and I got beer in mine that needs to be drained prior to bottling...however will I do that?!
The PET bottles to check for carbing is a good idea.
I also bought some Heiny ponies to use (again, after proper draining..
) as my test bottles, no need to pop a 12-22oz bottle just to test it.