Price: $0.01
Pros: Cheap, Lightweight
Cons: May Leach dangerous chemicals into alcohol. BPA etc. ("7" recycling code)
Recommended? No

Comments: Worked great, but concerns about chemical leaching caused me to get rid of them and never look back.

Price: $1.00
Pros: light weight
Cons: looks used but to be expected
Recommended? Yes

Comments: got this free from work, standard culligan style, lightweight yet sturdy, a great find if you can get them from around the office or craiglist

Price: $25.00
Pros: Not as nearly expensive as all them carboys out there and works just as good; buy the appropriate bung and you should be fine. Also if it falls, it won't shatter, unlike glass fermenters.
Cons: It's an Arrowhead water jug...'nuff said. Probably looked down upon by those who uses "better" equipment.
Recommended? Yes

Comments: Works remarkably well, just have to find the appropriate bung and stopper and gt the accurate width in which you'll be needing to hold it in place, but really, it works just fine for being TOTALLY unorthodox for beer-brewing.

Pros: Cheap, Durable, Easily Available
Cons: Harbors odors, O2 permeable
Recommended? Yes

Comments: I use them for secondarys for beer, but for wine which needs a lot longer time I wouldnt use them as they are pretty permeable to oxygen, as oppsed to glass which is 100% not permeable, and the BB which has a permeability of around 1 ppm per year. They definitely harbor odors, but I havent noticed a pickup in subsequent batches. The fact that they harbor odors means that the surface is porous, making them harder to clean than the BB which everything slides off.

Price: $5.00
Pros: Light weight. Almost indestructible.
Cons: Posibility of some o2 permiability, May scratch. Only 5 gal so best used as secondaries.
Recommended? Yes

Comments: I've been using Polycarbonate water bottles for extra carboys for years with no problems. And now after recently having a glass carboy break while dumping cleaning solution out (just broke on it's own, didn't even hit anything, bog junk came out of the carboy leaving a big nasty jagged hole in the side.) and having sharp glass all over the place, I'm inclined to start accumulating more of these.

Since they are 5 gal., they are best used for secondaries unless you don't mind losing half a gallon during blowout.