Dave, I think plastic bags are probably the worst proofing containers, as they maximize contact with the container and require lots of oil.
Here are traditional proofing panshttp://www.wasserstrom.com/restaurant-supplies-equipment/Product_600605
These are sized more for Neapolitan doughs, although, from my calculations, you should be able to fit 4 NY style balls (for 16" pies) if you stagger them. Earlier you mentioned M. Teixeira, are you in NJ? If so, Corrados in Clifton has these for around $12. The exterior dimension on the long end is 27" though, so my fridge isn't big enough. I also, at this point, tend to make 4 balls but only bake 2 balls at a time, which means I'd have to transfer the dough to other containers to warm up.
Here are the half size pans that I mentioned earlier:http://www.doughmate.com/artisanproducttrays.html
I'm pretty sure that although these are slightly smaller than 1/2 the regular size ones, 2 dough balls (16") should still fit. I'm not in love with the $40 (including shipping) price tag, though.
Most of the pizzerias in my area use aluminum proofing pans like these:http://www.bakedeco.com/detail.asp?id=12481&keyword=Related%20Items
These are pretty standard for slice places. Since most slice places work with same day doughs, the aluminum doesn't have much time to react with the acids in the dough. I don't think I want a two day dough sitting in aluminum for all that long, and, should I ever get into sourdoughs, the acid in those would definitely cross these off the list.
Here's what I'm using now:http://www.bakedeco.com/a/plastic-dough-pan-s-12232.htm
As I clicked on this link to confirm it, I notice that they now have a larger size:http://www.bakedeco.com/detail.asp?id=23241&keyword=Related%20Items
Had they offered these at the time, I definitely would have bought these instead, as my 16" doughs will sometime get past me and stick against the top of the smaller pans.
The big downside to these is that you can't see the bottom of the dough, which, for a beginner, is critical for detecting proper fermentation.
I'm not a huge fan of the size, but the Pyrex round glass 7 cup container works pretty well:http://www.amazon.com/Pyrex-Storage-7-Cup-Round-Plastic/dp/B000LOWN3C/?tag=pizzamaking-20
I've been keeping my eye out for larger round glass containers, but, so far, this is the largest and most easily found (walmart, target, kmart, etc.). I did come across this set from Italy:http://www.greenfeet.com/itemdesc.asp?kw=Glass-Round-Storage-Bowls-and-Lids-Set4-&ic=6007-00480-0000
As far as size goes, I really like the 12 cup capacity XL bowl, but I can't find it on it's own.
Your best bet would probably be to lose the clear bottom 'training wheels' as fast as possible (by detecting smell and knowing time frames for previous doughs with similar ratios/proofing conditions) and then graduate up to real proofing pans, either rectangular or round.