I know - I used them for my glass block bar! You best option is to visit a glass block contractor. Look in the yellow pages. They are very helpful. Their prices for standard blocks and mortar are comparable to the big boxes.
And AVOID the big boxes like Lowes and Home Depot. Their knowledge is limited (non-existant?) and the inventory the same.
You have several options, depending on how tight you want the curve. I did a 12" radius using "argue" blocks.