Oh the burps that it used to produce (from our baby, that is)!
However, our little boy grew out of his very quickly (by 4 months), and we needed to find an alternative.
We started using this small IKEA metal bin, and it worked just as well as the Tummy Tub. In fact, it was better as our baby would sit normally in it, instead of sitting in the rather odd yoga position as he did previously.
It's half the price of the Tummy Tub (£10.29) and has come in really useful since, as a little laundry basket.
Actually... I guess you could use any old, communal garden aluminium bucket from a hardware shop too. Now that would be even cheaper...