Rough math.. for 3,856 FP you can have a Lvl 10 HC providing 5 uses, with 25%.. for a further 3,715 FP (Lvl 15) you can boost that to 5 x 28.11%, and 4,406 (Lvl 16 gives 6 x 28.72
Or for another 3,856 you can add another 5 x 25% with a SC..
In GBG we negotiate at first for maximum points \ minimal goods before battling.. so ignoring a bunch of stuff.. 10 x 25% for same price as 5 x 28.71% (Ish)..