They're about 1,000 bucks per bladder. Labor is about 10 hours so anywhere between 800 and 1k in labor per. Comanches with the aux bladders have a total of 4. So you're looking at 1,800-2000 dollars installed, per bladder. Life cycle of a bladder should be in excess of 20 years but in practice with weathering, top of the bladders remaining dry for a long time due to flying with partial or even empty auxes all the time, you'd be looking at 10 years before these things start giving you trouble again. I prefer Piper's integral tanks; unfortunately Piper didn't really have a replacement to the comanche (I don't consider the Piper Lance a bona fide in-class replacement in the least, as Piper argued), so you're kinda stuck with these old Comanche contraptions if you want something between an Archer/Arrow/Dakota and a 6-place airplane like PA32 and A36 C210 et al. Their competition being the Beech 33/35 bonanzas of course, which also carry the expense and hassle of these bladders, to be fair to the comanche.

FUEL bladders although a pain sometimes... MUCH safer than metal or Wet wing tanks in survivable accidents ! they absorb impact better and may not rupture vs the other style... I'll take my bladders any day.. IMO