I don't think age has a lot to do with this choice. A simple black satin clutch with a bit of silver sparkle (or plain) would do the trick. Both your dress and shoes have a lot going for them, so my recommendation is to tone down the clutch. Then it also becomes a piece you can wear whenever you need a clutch. Check Zappos, Dillards, and Endless.com for online shopping. In person, check out T.J. Maxx, Marshalls, and Penneys.
Good luck.