Catherine, another place you might consider is a small shop in Crossfield I use. (Promold MArketting Inc.) They carry a lot of different sizes and styles. Nice thing is they also will either sell you the parts or install custom bulkheads and lids.
This is the 5 gal ATO bin I got from them. I liked the hopper bottom and wall mounting.
This one was already threaded for wall mounting and came with the 6" vented cap (it has a valve to relieve vacuum as the level drops). They also supplied me with my SW storage tank. A black 35 gal RV tank that I stood on end and fitted with a 6" vented lid.
I'm not sure how their prices compare with UFA, but I know they have a wide variety in shapes and sizes. I was checking out their 10,000 gal poly tank the other day....got me dreaming
Francis