Do you really need a travel case? My Sonicare HX6911/02 FlexCare Rechargeable purchased in 2010 has circled the globe many times and is still going strong. It goes in a zip-lock bag and then into a larger zip-lock that includes toothpaste, floss, and a few other things.

Using a water flosser has made an even greater dental hygiene improvement for me the past few years, so in a separate zip-lock is my Waterpik Cordless Advanced Water Flosser and mouthwash.