Thinkgeek used to sell them, I bought one for someone as a gift years ago, but I don't see them on their site any more (plus they're shutting down).

Amazon has some, might be listed as a light saber umbrella, like this one:

https://www.amazon.com/BESTKEE-LED-Umbrella-Lightsaber-Changing/dp/B01DNOVSAK/ref=sr_1_3?keywords=BESTKEE+Lightsaber+Umbrella&qid=1565655580&s=gateway&sr=8-3