Kalidasa,
That toy looks like tons of fun! I have always enjoyed going to pet stores and scoping out toys for all animals, especially birds. I have even done this at times that I couldn't have pets at all! I sometimes think that I enjoy the toys more then the birds do.
I had a small in cage bath for my budgies, but I had to take it out. They enjoyed it just a little to much, spreading water all over the inside. I live in North Carolina and with spring here, the temps are fairly high. Bacteria does not take long at all to grow and I was just to worried about the toys and other small spots in the cage growing bacteria.
What I use for my budgies now is a bird bath that I attach to the gate of the cage. They take a bath every day in it, and I just dry the areas that get wet afterwards. The main issue before was that they were bath four and five times a day so some areas just were not staying dry! I do clean the cage every morning, wiping down toys, perches, sides, and changing the bedding. I might be a bit to paranoid, but I don't think you can be to safe.