The Dries Von Noten show had beautiful gold rings encasing just-messy-enough pony tails. This is a very easy way to glam up a regular pony and can be done quite easily.
Use a small elastic or even better a clear one to secure your hair, then use an adjustable ring to hide it. I love the simplicity of the gold band, but also found some fun options on Zappos.
I bet if you searched your jewelry box you would find some costume pieces that would be perfect.