Same here, very pricey, when the tank came back is was about 30 lbs. heavier too ( In fairness the tank was very holey to begin with). If you just have a couple of pinholes or loose shit in there sloshing sealer is the answer.
I think industrial plastics and paint is selling the bill hirsch tank sealer kits now. If not I can get aircraft tank sealer but it aint cheap.