Seems about what they go for on the 'bay once you include shipping, I'd call it a fair price, not outrageous by any means.
I just saw some 4x5s go for $2.50 a sheet, and 120 rolls go for the same price as new Velvia too.
So it may be nearly double FP4 in either format, but APX just seems to command higher prices for whatever reason (and, having 3 boxes of 4x5, some in 120, and a bulk roll or two in 35mm, I'd be interested if I didn't already have more than I need).