I'll second rockstomper.com that's where I got mine from. Afterwards I did run across this place, which I haven't bought from but they seem to be competitive and potentially cheaper.

http://www.offroadoverstock.com/index.cfm

They sell Amsteel as well and have all sorts of hook options. If you are switching from the stock Warn hook you may want to upgrade or will need an adapter so that the hook will fit the thimble needed with synthetic. If you have a roughened roller fairlead then there is also the hawse to consider. I ended up with UHMWPE (plastic) but would likely go aluminum now since I've learned mine may flex too much allowing the line to rub on the steel opening.

And I might be up for going over there for kicks.
Geoff