Brew2bottle will sell you a 25 litre plastic FV for about £7 and a 15 litre one for about £4. I've just replaced one of my 5 year old 25 litre bins with a new one, since it was beginning to get a little tainted, and bought two 15 litre ones for smaller brews.
These items, at less than £10, will be perfectly satisfactory for the majority of brewers, they are cheap to replace and do the job. A 33 litre plastic FV is fine if you brew slightly larger volumes or you want to guarantee keeping the brew inside the FV at all atimes. And I would buy one on that basis , but I only brew 22litres and less, and have only had two brews in over 100 since restarting brewing which have tried to escape the FV at the beginning of the primary.
On the downside I'll bet most plastic FVs leak at the rim to lid seal, but to me that's not a problem, If I want to see airlock bubbles, and I think the lid to FV seal is leaking, I just use four strips of cling film over the rim of the FV which does the job.
for £7 from 
