Sunshine Marine is good. I had mine made by RDS in Perry, Florida. 28 gallons with baffles, custom-made to match the original. It listed at just under $400 in '05.
I have to admit, though, it was given to me free because the VP-CFO of ProLine boats was a parishioner of mine, and RDS comp'd the tank as a "display model".
Often, it's not what you know, it's
who you know,
(and whether you're willing to shamelessly ask for favors.) 
__________________
Common Sense is learning from your mistakes. Wisdom is learning from the other guy's mistakes.
Fr. Frank says:
Jesus liked fishing, too. He even walked on water to get to the boat!
Currently without a SeaCraft 
(2) Pompano 12' fishing kayaks
'73 Cobia 18' prototype "Casting Skiff", 70hp Mercury