We have one of the $35 Duckworks pump-up showers, linked above. This is just a thumbs-up vote for it. Really a pleasure.
This is the one we have too. I emailed Duckworks to ask a question before ordering, and got a fast, friendly reply. Very happy with the service and the product. We were going to make our own but could only find clear 2-gal garden sprayers in stores around here and wanted black to better heat the water on a sunny day.