Looking to treat my 1.6 acre pond with Fluridone.

Does anyone have any recommendations on a good generic brand(similar to sonar) and where to purchase from?

I will probably have to do this every year so looking for something cost effective.

The types of weeds I'm treating are located in this post
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=449479&gonew=1#UNREAD

Thanks!