Gas tank clean and seal cost?

[supergnat]

I have developed a small leak around my fuel gauge and figure I should just pull the entire tank and have it cleaned and sealed while I am repairing the gauge leak. The only place I can find in my area (NJ next to Phila, PA) said it would cost about $250-$300 to have the tank cleaned and sealed. Is this what I should expect to pay or should I just keep looking? I would prefer to keep my original tank if possible since it original to the car (10-2-28).

Thanks for your advise