I bought the Stephen Joseph Watermelon Umbrella (and the Butterfly one, under a separate listing) from Amazon and am pretty pleased.  They are bright and colorful, sized correctly for a three year-old, and durable enough to survive moderate use.  These are replacements for toddler sized umbrellas from another brand (I can't remember which, they make matching raincoats) that broke after one use.  The previous umbrellas were vinyl, glued to the thin aluminum spokes.  When the spokes were stressed the vinyl tore immediately and the spokes were stressed as soon as any weight was put on the sides of the umbrella.  This umbrella by Stephen Joseph is built more like an adult's umbrella with safety features for a child.  The tip is protected by a plastic ball (I had to re-glue one of them, but it was pretty easy),and the spokes are also protected by sturdy plastic tips.  The open/close mechanism is buttonless and easy to engage just by pushing up the center along the shaft.  The waterproof nylon material is hooked to the spokes with little thread loops.

The kids play with it around the house while it's closed; using it as a cane or a big stick or a hook.  It's survived this so far, but I've cautioned them every time I see them playing with it.  I think these are built in a reasonable fashion for kids and with very nice designs.  I'd definitely purchase these again until the girl's outgrow them.