I do not have knowledge of this company but if you want to find a specific piece on ebay made by them, I would set up a "Saved Search" on ebay that alerts you to new Dugan Glass listings. You will get periodic email alerts.
I would also be searching around for a dealer who specializes in 20th century glass and let that person know what you are looking for.
It is definitely worth taking the time to learn how to send a photo since no matter who you are in touch with will greatly benefit by seeing the picture