someone here posted a link for one i wanted to get. it had a 45 degree cut on one end too and was about $8.00. wish i could find that link again!!! for joining your binding ends. found it-
http://www.quiltingboard.com/t-47471-1.htm
it was one mentioned here.
i also have the one for bringing your backing over and using it as binding. miters the corner. it's green i think buti haven' t used it yet.