I had some thing similar - but from a hardware store. Really useful piece of kit. I put bricks in the bottom so that the drained hay wasn't sitting in the few inches of water that can't drain out of the bottom because of the level of the tap.
If you're going to use a water butt, make sure it's a round one and not one which has joins in it (the one in the picture is one with joins). I made this mistake and they start leaking after a very short period of time. I took it back and heard the chap say to another member of staff as he took it away that this was a known problem.
On the plus side, a round water butt with a plastic riddle upside down in the bottom and a hosepipe attached to despatch the used water is brilliant - makes soaking hay so much easier.