If you want a good value day out photographing Red Kites you could go to Gigrin Farm in central Wales. You can go into the hides and in winter see hundreds of Kites wheeling around waiting for their chance to swoop down on the meat provided.
I have found another great place though, Bwlch Nant yr Arian Forest Visitor Centre in Ceredigeon. They fly in over a small lake and when most of the food has been taken they will go for the floating bits left in the water. See below.