Bill D., one option to expanding your current pond is instead just create a second one.
I don't know your situation and that might not be an option for you (land availability, location etc.). But it is often cheaper to create a new pond than expand an existing one. I've built new and cleaned out and expanded old (granted your expansion would not be nearly as bad as cleaning the muck out of an old pond) and can tell you from first hand experience, creating new is a lot easier.
You might find it as cheap or cheaper to build another 1/4 acre pond adjacent or back to back to your existing pond as it would be to expand the current one by 1/8. Two ponds gives lots more management options than a single pond, although a larger pond often is better aesthetic wise.
Just something to think about if it is an option in your situation.
