Speaking of high-side power switches with protection and diagnostic functions, have you read Infineon's ADVANCED SENSE Calibration and Benefits guide (http://tinyurl.com/ADVANCED-SENSE-1-0)?
As an aside... I happen to know that the guys who wrote this little rascal are incredibly clever and handsome and witty ... the words all appear to have been hand-picked at the crack of dawn while the morning dew is still glistening on them, and it goes without saying that the quality of the diagrams is fantastic...
This is an incredibly complex question. What is a good price for me is really expensive for someone designing for the mass market. Before I overwax philosophical though, it seems to me you are only interested in a single unit, so I will only state the price from Digikey for the automotive version AUIR3314S is C$4.81. (C$1 is approx US$1.) Apparently it is still available in a TO220 pack, if you want ease of connection although you may struggle to find it in that format although I see Digikey have 6 at C$6.95 at the moment and Mouser have it in abundance.
Thanks, Aubrey. I was thinking of using it on an analogue variable power supply, before the main pass transistor. Apart from being able to switch the output off electronically, you could get a ground-referenced voltage proportional to output current - very useful for measuring output current using a standard DVM module - which on a variable PSU is otherwise not easy.. Looking at the specs for your IR3314, I think it would work ok. I'll look at the others as well. Are these things expensive?