IIRC there are signs in Beis Yeshaya advertising them.
Lol, I don't think the signs ever lasted more then a day or two, before the cleaning crew comes along to clear all the signs.
On malchai yisroel by one of the toy stores walking from kikkar shbs on the left side, they had very decent umbrellas for a decent price, better quality and decent prices then elsewhere.
I picked up an umbrella to buy but she couldn't get my cc to work, i tried 3 of them (3 cc's) before I lost patience and continued walking in the drizzle.(something must have been wrong with her cc terminal).